Soil heavy metals in tropical coastal interface of eastern Hainan Island in China: Distribution, sources and ecological risks

•Multiple residues of heavy metals were firstly studied in tropical coastal soil.•The average contents of heavy metals were in order of Cr > Zn > Pb > Cu > Ni > As > Cd > Hg.•25% and 5% sites were moderate or extreme ecological risk due to As and Cd accumulation.•As pollution was related to land use types with the largest risk in northeast cropland.•Human activities and soil parent materials contributed to 64% and 36% of pollution source.