Heavy metal uptake in Spinacia oleracea and Coriandrum sativum from wastewater irrigation

Abstract

Vegetables are vital for human nutrition but can accumulate heavy metals, posing risks to public health and the environment, particularly in regions using wastewater for irrigation. This study, conducted in Gujranwala, Pakistan, evaluated heavy metal contamination in wastewater, soil, Spinacia oleracea L., and Coriandrum sativum L. using Atomic Absorption Spectrophotometer (AAS). A total of three samples were collected per matrix. Plant and soil samples were digested using a tri-acid mixture (HNO3: H2SO4: HClO4) at 80 degrees C, and AAS calibration was performed with standard solutions. Detection limits were within 0.01-0.05 mg/kg. Results showed that various heavy metals surpassed WHO allowable limits in both vegetables and irrigation water. In spinach, Co (0.292 mg/kg), Cr (2.55 mg/kg), and Pb (0.476 mg/kg) surpassed the WHO thresholds of 0.1, 2.3, and 0.3 mg/kg, respectively. In coriander, Co (0.227 mg/kg), Cd (0.288 mg/kg), and Pb (0.457 mg/kg) exceeded the WHO limits of 0.1, 0.2, and 0.3 mg/kg, respectively. Although soil levels stayed below WHO limits except cadmium, wastewater analyses showed concentrations of Co (0.072 mg/L), Cd (0.023 mg/L), Cr (0.117 mg/L), and Pb (0.226 mg/L), surpassing the WHO thresholds for irrigation water of 0.05, 0.01, 0.05, and 0.05 mg/L, respectively. These exceedances underscore possible dangers from wastewater irrigation and eating contaminated vegetables in the study region. The findings underscore the urgent need for sustainable irrigation practices and land management to mitigate heavy metals bioaccumulation and safeguard food safety. These findings highlight the need for implementing wastewater treatment systems and establishing routine monitoring to ensure food safety. This research supports SDG objectives 2, 3, and 6 by emphasizing the importance of safe irrigation methods and safeguarding food quality and public health.