As the "lungs of the city ", urban forests can improve air quality by absorbing air pollutants, becoming hotspots for mercury (Hg) pollution from anthropogenic activities. However, the bioaccumulation and transfer of Hg in the urban forest food web are unclear. In this study, total mercury (THg) and methylmercury (MeHg) concentrations, as well as the stable isotopes of carbon (delta C-13) and nitrogen (delta N-15) in organisms with different trophic levels (TLs) were investigated in a mid-subtropical urban forest of the Changpoling Forest Park (CFP) in Guiyang City, Guizhou Province, southwestern China. The results showed that THg and MeHg among all taxa ranged from 5.6 to 1267 ng g(-1) and 0.046-692 ng g(-1), respectively. MeHg% (% of Hg present as MeHg) at different TLs exhibited a wide range of 5.0-69% on average. Both THg and MeHg increased with the TLs from plants to nestling birds, indicating distinct biomagnification through the food web of grasses/pine needles -grasshoppers/ caterpillars/katydids/mantis -spiders/songbird nestlings. The trophic magnification slope (TMS) of THg and MeHg were 0.18 +/- 0.05 and 0.37 +/- 0.08, respectively, suggesting both of them significantly increase along food webs. These findings improve the understanding of biogeochemical Hg cycles in terrestrial food webs and highlight the impacts of terrestrial MeHg on nestling birds.

Publication name	CHEMOSPHERE, Volume 299, Article Number 134424, DOI 10.1016/j.chemosphere.2022.134424, Published JUL 2022, Early Access MAR 2022
Author(s)	Zhang, Fudong; Xu, Zhidong; Xu, Xiaohang; Liang, Longchao; Chen, Zhuo; Dong, Xian; Luo, Kang; Dinis, Faustino; Qiu, Guangle
Corresponding author(s)	Chen, Zhuo  chenzhuo19@163.com  Guizhou Normal Univ, Sch Chem & Mat Sci, Guiyang 550001, Peoples R China  Qiu, Guangle  qiuguangle@vip.skleg.cn  Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Guiyang 550081, Peoples R China
Author(s) from IGCAS	Qiu, Guangle; Zhang, Fudong; Xu, Zhidong; Xu, Xiaohang; Luo, Kang