Because　mercury　and　ethylenediaminetetreaacetic　acid　(EDTA)　are　widely　used　materials　and　are　commonly　found　together　in　the　environment　due　to　anthropogenic　and　industrial　releases,　there　is　a　great　need　to　develop　a　bifunctional　sensor　for　both　mercury　and　EDTA.　A　fluorescent　sensor　SQ-1　based　on　a　squaraine　chromophore　with　dithiocarbamate　(DTC)　side　arms　has　been　prepared,　and　its　aggregation　behavior　in　aqueous　solution　has　also　been　investigated.　The　results　show　that　increasing　water　concentration　in　the　solution　causes　dramatic　H-aggregation　of　the　symmetric　SQ-1　and　consequently　provides　a　mercury　probe　with　a　visual　color　change　and　＇turn　on＇　fluorescence　via　cation　induced　deaggregation.　EDTA,　a　strong　chelator　to　mercury,　accelerates　the　deaggregation　process　and　enhances　the　fluorescent　emission,　which　not　only　improves　the　sensitivity　of　SQ-1　to　mercury　by　10-fold,　with　a　detection　limit　improvement　from　1.1　×　10-7　M　to　1.3　×　10-8　M,　but　also　provides　a　way　for　trace　level　detection　of　EDTA,　with　the　detection　limit　of　8.7　×　10-8　M.　The　potential　application　of　this　technique　for　Hg2+　and　EDTA　determination　of　river　water　samples　is　revealed　by　proof-of-concept　experiments.　©　2014　Elsevier　B.V.　All　rights　reserved.