Element concentrations in water spinach (Ipomoea aquatica Forssk.), fish and sediment from a wetland production system that receives wastewater from Phnom Penh, Cambodia

The Cheung Ek Lake, which is located south of Phnom Penh, Cambodia, receives most of the industrial and domestic wastewater that is produced in the city. The lake is used for fishing and production of water spinach (Ipomoea aquatica Forssk). Concentrations of 35 elements were determined in water spinach and sediment that were collected along transects of two wastewater inlets in the lake, at the lake outlet, and in a non-wastewater exposed pond. Elevated concentrations of the potentially toxic elements (PTEs) Cd, Cu, Ni, Pb, Sb, and Zn were found in the water spinach and sediment samples collected near the wastewater inlets. The highest determined PTE concentrations in water spinach were, in mg kg- 1 fresh weight (f.w.), As 0.19, Cd 0.022, Cu 2.95, Fe 251, Pb 0.206 and Zn 9.08. For an adult person in Phnom Penh, the maximum intake of PTEs from consumption of water spinach harvested near the wastewater inlets amounts to 5.7% As, 1.4% Cd, 0.4% Cu, 20.5% Fe, 3.8% Pb and 0.6% Zn of the maximum tolerable intake set by the Codex Alimentarious Commission. Arsenic, Cd and Pb concentrations in the liver, skin, and muscle of three fish species caught in the lake were below or near the detection limits, except for a high accumulation of the three elements in the skin of the blackskin catfish. In conclusion, the consumption of water spinach and fish from Cheung Ek Lake constitutes a low food safety risk with respect to PTEs.