title: High levels of methylmercury in guano and ornithogenic coral sand sediments on Xisha islands, South China sea.
abstract: This study determined the distribution and main source of methylmercury in ornithogenic coral sand sediments and pure guano collected from Guangjin and Jinqing islets of the South China Sea. Results showed that the levels of methylmercury (MeHg) and total mercury (THg), as well as the percentage of MeHg relative to THg (%MeHg), are high in both fresh and ancient guano samples. %MeHg in ancient guano exceeded 70 %, much greater than that in fresh seabird droppings (~45 %). These results suggest that excretion through feces likely plays an important role in the cycling of MeHg by seabirds. Guano has been identified as the major source of MeHg in the ornithogenic coral sand sediments in the Xisha Islands. The close relationship between MeHg and guano-derived phosphorus has weakened considerably since 1840 AD. This is probably caused by a significant increase in THg and MeHg in modern guano samples due to the recent increase of Hg pollution. %MeHg in the ornithogenic coral sand sediments is extremely high, ranging from 10 to 30 % (average 20 %).
authors.affiliation: Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, China.
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Chen
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Liu
authors.forename: Liqiang
authors.initials: L
authors.lastname: Xu
authors.forename: Liguang
authors.initials: L
authors.lastname: Sun
authors.forename: Hong
authors.initials: H
authors.lastname: Yan
authors.forename: Yi
authors.initials: Y
authors.lastname: Liu
authors.forename: Yuhan
authors.initials: Y
authors.lastname: Luo
authors.forename: Jing
authors.initials: J
authors.lastname: Huang
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000737:chemistry; D001717:Birds; D002681:China; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis*; D004787:Environmental Pollution / Q000032:analysis* / Q000706:statistics & numerical data; D005243:Feces / Q000737:chemistry*; D005843:Geography; D019015:Geologic Sediments / Q000032:analysis / Q000737:chemistry*; D008628:Mercury / Q000032:analysis*; D008767:Methylmercury Compounds / Q000032:analysis*; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D004785:Environmental Pollutants; D008767:Methylmercury Compounds; D012822:Silicon Dioxide; D008628:Mercury