Rainwater　brings　considerable　amounts　of　dissolved　organic　matter　(DOM)　from　atmosphere　to　freshwater　and　marine　environments,　but　little　is　known　about　the　chemical　composition　and　bioavailability　of　rainwater　DOM.　The　quantity,　quality,　and　bioavailability　of　DOM　were　investigated　for　21　rain　events　at　a　coastal　site　in　southeast　China,　using　dissolved　organic　carbon　(DOC)　measurements,　absorption　spectroscopy,　and　fluorescence　excitation-emission　matrices-parallel　factor　analysis　(EEM-PARAFAC).　The　DOC　concentration　ranged　from　35　to　457　mu　M,　which　was　affected　by　the　prevailing　monsoon,　rainfall　amount　and　terrestrial/anthropogenic　inputs.　The　volume-weighted　average　DOC　was　118　mu　M,　corresponding　to　a　rainwater　DOC　flux　of　1.98　g　m(-2)　yr(-1),　Four　fluorescent　components　were　identified　with　EEM-PARAFAC,　including　three　humic-like　components　(C1-C3)　and　one　tyrosine-like　component　C4.　Absorption　coefficient　(a(CDOM)(300))　and　fluorescence　intensities　of　C2-C4　strongly　correlated　with　DOC,　indicating　they　can　be　used　for　DOC　estimation.　Rainwater　DOM　was　characterized　by　low　DOC-specific　UV　absorbance　(SUVA(254))　and　humification　index　(HIX,　which　indicated　a　low　aromaticity　and　humification　degree.　Principal　component　analysis　(PCA)　based　on　DOM　indices　revealed　two　principal　factors,　which　were　related　to　the　DOM　concentration　and　humification　degree　respectively.　PCA,　together　with　air-mass　trajectory　analysis,　successfully　separated　different　rain　events　with　variable　inputs　from　living　plants/local　sources,　soil　organic　matter/humifiecl　materials,　and　the　marine　source,　Rainwater　DOM　generally　showed　a　high　bioavailability　of　50%　+/-　19%,　with　higher　degradability　of　non-chromophoric　constituents　and　C1-C2　than　other　components.　This　study　demonstrated　the　applicability　of　absorption　and　EEM-PARAFAC　combined　with　PCA　and　air-mass　trajectory　analysis　in　differentiating　rain　events　and　tracking　organic　matter　sources,　and　revealed　different　effects　of　microbial　degradation　on　individual　PARAFAC　components　in　rainwater.