<p>Identification and quantification of allochthonous and autochthonous organic carbon (OC) are crucial for the interpretation of burial behaviors of sedimentary OC of shallow lakes under anthropogenic interferences. In this study, we analyzed distribution patterns and δ<sup>13</sup>C signatures of mid- and long-chain <em>n</em>-alkanes on various types of surface samples from a typically large and shallow Lake Wuliangsu in the Hetao Irrigation District. The results indicate that <em>n</em>-alkanes among submerged macrophytes, emergent plants, and riverine soil show unique distribution patterns and δ<sup>13</sup>C signatures, supporting the practicability of quantification on OC of these sources by end-member mixing models. Introducing the δ<sup>13</sup>C values of <em>n</em>-alkanes into the end-member mixing models could effectively reduce the potential error derived from end-member determination on <em>n</em>-alkane distribution patterns and OC degradation. The model results suggest that the riverine sourced OC from the main channel to Lake Wuliangsu has settled down during the southward migration process. Therefore, Lake Wuliangsu serves as an important trap and sink for the allochthonous OC from the Upper Yellow River Reaches. The model results also show a predominate contribution from the autochthonous OC to Lake Wuliangsu (mostly >85 %), with open-water areas dominated by submerged macrophytes and the rest of areas by emergent plants, largely modulated by water transparency, water depth, and nutrient concentrations. Together with previously published tetraether results, we further proposed that areas dominated by submerged macrophytes might be more favorable for heterotrophic anaerobic bacteria and methanogenic archaea, largely due to active recycling processes for the labile OC derived from submerged macrophytes.</p>