Exchangeable lead (Pb) in lowland paddy soils of Sri Lanka as affected by the differences in agro‐climatic zones, soil orders, and water sources

Societal Impact Statement Lead (Pb) accumulation in the human body poses serious health risks. As rice is the staple food in Sri Lanka, with a high per capita intake (114 kg), there is a significant risk of Pb transfer through rice consumption. This study evaluated exchangeable Pb concentrations in soils and produced Pb distribution maps. These maps can guide area‐specific decisions on suitable rice cultivation areas to reduce Pb bioaccumulation in grains. Such informed planning can help protect public health and well‐being, and enhance the livelihoods of local farmers, contributing to safer food production across Sri Lanka. Summary Excessive concentrations of the exchangeable form of lead (Pb) present in soils in which rice is grown pose a threat to human health due to its accumulation in rice grains. This is particularly important for communities where rice is consumed as the staple food. Despite this, the current status of Pb in Sri Lankan rice soils is not known. Therefore, this study was conducted to determine the concentration of exchangeable Pb among agro‐climatic zones (ACZs), soil orders, and water sources in Sri Lankan paddy soils. Exchangeable Pb in 5,168 soil samples representing six ACZs, six soil orders, and three water sources was extracted into 0.01 M CaCl 2 and detected using inductively coupled plasma mass spectrometry (ICP‐MS). Exchangeable Pb concentration ranged between 0.02 and 832 μgkg −1 with a mean concentration of 42.5 μg kg −1 . Samples collected from the Wet zone Low country had a higher Pb concentration than other ACZs ( P < 0.05). Among the soil orders, Histosols had the highest Pb concentration while that in Alfisols was the lowest ( P < 0.05). Water sources used (i.e. irrigated or rainfed) had the least impact in determining Pb concentration. Moreover, Pb concentration was negatively correlated with soil pH ( P < 0.05). Maps were generated to identify paddy fields with low and high exchangeable Pb levels. These represent an important resource as they can be used to make area‐specific agronomic and administrative decisions concerning rice cultivation. The net effect will be improved management of rice‐growing soils with positive impacts on human health and the livelihood of local rice farmers in Sri Lanka.