The　contamination　of　micro-plastics　(MPs)/nano-plastics　(NPs)　in　environment　poses　a　global　concern,　necessitating　a　scientific　evaluation　of　their　potential　risks　to　ecosystems　and　organisms.　We　herein　investigated　the　adsorption　kinetics　of　different　mercury　species　including　inorganic　mercury　(Hg2+),　methylmercury　(MeHg)　and　ethylmercury　(EtHg)　on　three　different　MPs,　such　as　polyethylene　MPs　(PE　MPs),　polypropylene　MPs　(PP　MPs)　and　polystyrene　MPs　(PS　MPs)　in　micro-polluted　water　in　detail,　and　further　evaluated　the　individual　and　combined　cytotoxicity　of　polystyrene　NPs　(PS　NPs)/polypropylene　NPs　(PP　NPs)　and　different　mercury　species.　The　results　indicated　that　EtHg　undergoes　demethylation　partly　to　form　Hg2+　during　the　adsorption　process　on　PP　MPs,　and　the　adsorption　kinetics　of　Hg2+,　MeHg　and　EtHg　on　three　MPs　fitted　with　pseudo-first-order　(PFO)　model　in　initial　stage　and　simultaneously　fitted　with　pseudo-second-order　(PSO)　model　during　whole　adsorption　process.　This　suggested　that　adsorption　of　mercury　species　on　three　MPs　we　driven　mainly　by　physical　process　in　initial　stage　and　by　chemical　process　during　whole　absorption　process.　In　natural　micro-polluted　water,　the　equilibrium　adsorption　capacities　(Qe)　of　Hg2+　on　three　MPs　(156.3–270.3　ng/g)　are　much　higher　than　that　of　MeHg　(5.562–78.13　ng/g)　and　EtHg　(7.831–70.42　ng/g).　Cytotoxicity　experiments　revealed　that　PP　NPs　and　PS　NPs　themselves　have　little　cytotoxicity,　but　the　presence　of　them　can　enhance　the　cytotoxicity　of　mercury　species,　showing　NPs　size-depended　and　mercury　species-depended　synergistic　toxic　effect.　The　findings　of　this　study　provided　valuable　insights　for　scientifically　evaluating　the　potential　risk　of　MPs/NPs　to　ecosystems　and　organisms.　©　2025　Elsevier　B.V.