Insight into Seasonal Dynamics of DOM and Analysis of Various Factors Influencing Microbial Communities from Typical Water Bodies: Based on Gray Influence Analysis and Structural Equation Modeling

This study investigates seasonal dynamics of dissolved organic matter (DOM) and their impacts on microbial communities across five aquatic environments in the Liaohe River Basin, China. Spatial-temporal variations in DOM composition and bacterioplankton community structures were evaluated using excitation–emission matrix (EEM) spectroscopy, parallel factor (PARAFAC) analysis, 16S rRNA amplicon sequencing, gray influence analysis (GINA), and structural equation modeling (SEM). Principal component analysis revealed pronounced seasonal variations of DOM in urban rivers and estuaries, whereas DOM dynamics in lakes were primarily driven by precipitation. Reservoir DOM showed significant fluctuations aligned with summer floods. GINA identified eutrophication-related DOM component C5 as the primary factor influencing microbial communities in lakes and reservoirs, while industrially derived DOM component C6 markedly affected bacterioplankton in river environments. SEM further quantified these influences, highlighting temperature and industrial inputs as critical drivers. These findings provide crucial insights into DOM-microbial interactions, emphasizing adaptive water management strategies tailored to distinct DOM sources and seasonal conditions to preserve ecological health and water quality in complex catchments.