Heavy metal concentrations and speciation of soil affected by bird droppings in Tongli Wetland Park, East China

The heavy metal content and speciation in soil and bird droppings from Tongli National Wetland Park were determined. The main purpose was to understand the impact of bird droppings on wetland soil heavy metal contentraions and their speciation changes. Soil with and without bird droppings was collected from Tongli Wetland. The metal concentrations were determined by inductively coupled plasma-optical emission spectrometry. The result suggested that the average pH for soil was 4.5, and the contents of N, C, H, S, and TP were 3.69, 38.07, 10.97, 0.52, and 1.43 g/kg, respectively. Thus, the N, C, H, and S levels in soil containing bird dropping were significantly higher than those in soil without bird droppings. The average contents of Cu, Zn, and Co were in the order guano sediments > soil with bird dropping > soil without bird droppings. The average content of Cr was in the order guano sediments > soil without bird droppings > soil with bird dropping. The average content of Ni was in the order soil with bird droppings > guano sediments > soil without bird droppings. In general, the Cu, Zn, Co, and Ni contents in soil increased with the presence of bird droppings. Bird droppings should be cleaned in a timely manner to reduce the local pollution risk of heavy metals in soil. The percentages of total active Co, Cr, Cu, and Zn fractions in soil containing bird droppings were slightly lower than those in soil without bird droppings. The inactive state showed an upward trend. The proportion of the total activity of heavy metals in soil reduced with the presence of guano, but the content of total and active heavy metals in the soil increased; therefore, the amount of migration of plant systems will increase, and fertilization using bird droppings should be applied carefully.