Ecotoxicological Risks of Trace Metals in Peri-Urban Food Garden Soils of the Industrial City of Lae, Papua New Guinea

Excessive concentrations of trace metals in soils in quantities above the allowed limits are dangerous to biota, ecosystems, and human health, especially when they enter the food chain through contaminated crops. Peri-urban subsistence food gardens in Lae city, Papua New Guinea, play an important role in household food security by providing a significant amount of dietary energy. However, rapid urbanization, industrial expansion, and other anthropogenic activities contaminate food garden soils with trace metals. This study investigated the concentrations, contamination status, and ecological risks of Cd, Cr, Ni, and Pb in peri-urban food garden soils in Lae City. Soil samples were taken at three depths (0–10, 10–20, and 20–30 cm), and metal concentrations were measured using inductively coupled plasma-optical emission spectroscopy, and contamination and environmental risk indicators were evaluated. Cadmium, Ni, and Pb concentrations surpassed WHO/FAO standards in 93.3%, 100%, and 10% of samples, respectively. The contamination factor, geo-accumulation index, and ecological risk indices consistently identified Cd as a significant ecological threat. While Cd and Pb were predominantly linked to anthropogenic activities, Ni and Cr appeared to originate mainly from geogenic sources. These results highlight the need for targeted monitoring and management strategies to safeguard soil quality and public health.