Heavy metal accumulation in rice paddy soils and grains irrigated with polluted river water in Indonesia

Irrigation of farmlands with contaminated river water poses a growing threat to agricultural sustainability in developing countries. This study assessed the accumulation of lead (Pb), cadmium (Cd), chromium (Cr), copper (Cu), and zinc (Zn) in paddy soils and rice grains irrigated with polluted river water in West Java, Indonesia, compared to a control site supplied with clean irrigation water. Irrigation water, soil, and rice samples were analyzed using atomic absorption spectrophotometry. Results revealed significantly higher concentrations of Pb, Cd, Cr, Cu, and Zn in polluted soils and rice grains compared to the control site. Notably, rice from the polluted site exceeded Codex Alimentarius food safety limits for Pb (0.40 ± 0.05 mg/kg) and Cd (0.30 ± 0.04 mg/kg). Basic soil parameters (pH, organic carbon, available P, and total N) showed no major differences between sites, indicating that heavy metal accumulation occurred independently of soil fertility indices. Correlation analysis indicated that soil pH was negatively correlated with Cd concentration, while soil organic carbon was positively correlated with Zn. These findings confirm that wastewater irrigation leads to substantial heavy metal accumulation, threatening food safety in affected regions. The study underscores the urgency of regular monitoring, stricter industrial waste management, and safer irrigation practices in Indonesia.