Study　Region:　This　study　is　conducted　in　the　southeastern　coastal　city　of　Fuzhou,　China.　Study　Focus:　Carbon　emissions　have　significantly　increased　under　the　rapid　urbanization.　Wet　deposition　(rainwater)　serves　as　a　major　sink　for　atmospheric　organic　carbon　(OC)　and　acts　as　a　potential　source　of　dissolved　organic　carbon　(DOC)　in　the　Earth＇surface.　This　study　aims　to　clarify　the　status,　variations,　sources,　and　deposition　flux　in　rainwater　DOC　in　coastal　urban　hotspot　area,　in　order　to　enhance　the　understanding　of　atmospheric　OC　in　coastal　area.　New　Hydrological　Insights　for　the　Region:　The　analysis　revealed　that　the　rainwater　DOC　volume-weighted　mean　(VWM)　concentration　during　the　study　period　was　1.77　mg　C　L-¹,　with　an　associated　deposition　flux　of　2.02　g　C　m-²　yr-¹.　The　dilution　effect　of　continuous　precipitation　affects　the　rainwater　DOC　concentrations.　In　addition,　the　concentration　of　rainwater　DOC　in　Fuzhou　was　influenced　by　atmospheric　OC　from　long-distance　migration　and　local　inputs.　Characteristic　ion　ratios　and　positive　matrix　decomposition　(PMF)　model　revealed　that　anthropogenic　emissions　driven　by　industrial　activities,　fossil　fuel　burning,　and　traffic　contribute　93.7　%　to　rainwater　DOC.　The　estimation　of　atmospheric　wet　deposition　contributed　1.82　×　105　t　yr−1　of　OC　to　Taiwan　Strait,　dominating　the　external　DOC　input　with　a　proportion　of　67　%.　This　work　gained　insights　into　the　wet　deposition　process　of　atmospheric　OC　in　coastal　cities　and　underscored　the　importance　of　this　process　in　the　global　carbon　cycle.　©　2025　The　Authors