Spatial variation in bacterial community and dissolved organic matter composition in groundwater near a eutrophic lake

The aim of this study was to reveal the variation in dissolved organic matter (DOM) components, bacterial community composition, and their co-relationships during groundwater migration. A well-studied shallow eutrophic lake, Lake Taihu, was selected to explore the DOM components and bacterial communities during groundwater replenishment from the lake using three-dimensional fluorescence-parallel factor analysis and high-throughput sequencing, respectively. Six fluorescent components of DOM were identified, including four humic-like components (C1: λ_Ex/Em=330/400 nm , C2: λ_Ex/Em=260, 350/450 nm , C3: λ_Ex/Em=270, 380/480 nm , and C6: λ_Ex/Em=220/410 nm ) and two protein-like components (C4: λ_Ex/Em=230, 280/320 nm , C5: λ_Ex/Em=230, 290/340 nm ). With increasing distance to Lake Taihu, the fluorescence intensity of C1, C3, C4, and C5 decreased within 15 km away from lake shore and then tended to be stable. Thirty-three phyla of bacteria were identified in the aquifer, including Proteobacteria (61.9