mercury and mercury speciation

bird droppings

soil contamination

wetland

Pollution

Heavy metals contamination of soil

This study investigates the effects of bird droppings on mercury pollution levels in soil, specifically on the speciation and total concentration of mercury (Hg) in soil from Tongli Wetland, East China. Thirty soil samples and four bird dropping samples were collected from Tongli Wetland along with fifteen eggshells and five feathers from Heron Branch birds. Results indicated that bird droppings affect local soil’s physic-chemical properties and Hg accumulation. Additionally, heron feathers were found to contain more total mercury (HgT) than their eggshells. Hg concentration in soil that is affected by bird dropping was determined to be 0.194±0.026 mg/kg; concentration in soil without bird droppings was 0.104±0.039 mg/kg. Therefore, HgT concentration in the former exceeded that of the latter (86.54%). Numerical analysis revealed that concentrations of water-soluble (F1), acid-soluble (F2), alkali-soluble (F3), hydrogen peroxide-soluble (F4), and residual mercury (F5) in soil that is affected by bird dropping were higher in soil that isn’t affected by bird droppings. However, concentrations of F1 remained mostly stable. We found a positive correlation between Hg concentrations in soil and excrement and concentrations of total carbon (C_tot), total nitrogen (N_tot), and hydrogen (H), in addition to an exponential proportional relationship between C/N and Hg/C. We concluded that fresh bird droppings in soil may promote mercury enrichment. Furthermore, bird droppings and highly decomposed humus increase soil HgT concentration when they remain in soil for an extended period of time.