Solar irradiation can induce the breakdown of particulate or dissolved organic matter and cause the release of inorganic nutrients. Lakes in the arid and semi-arid regions of northwestern China are exposed to high levels of ultraviolet (UV) radiation, yet the photochemical release of inorganic nutrients from resuspended sediments remains largely unexplored. In this study, sediment suspensions in 15 lakes of northwestern China were exposed to simulated UV irradiation, and the photochemical release of ammonium (NH4+) and phosphate (PO43-) were investigated during the incubations. The release and compositional changes of dissolved organic matter (DOM) were also explored by measuring their UV-Visible absorption spectroscopy and three-dimensional fluorescence spectroscopy. Results showed that light irradiation induces NH4+ and PO4 3-releases from sediment suspensions from most lakes, with rates ranging from undetectable to 0.42 mg N L-1 d-1 and 0.012 mg P L-1 d-1, respectively. Light irradiation also induces compositional changes in the DOM pools of sediment suspensions, producing DOM with smaller molecular sizes and lower aromaticity compared to dark controls. The NH4+ photorelease was influenced by sedimentary particle size distribution and extractable DOM abundance, with finer particles and higher sediment organic matter content contributing to greater NH4+ release. The PO43-photorelease linked closely to the humification degree of sediment extractable DOM. These findings suggest that photochemical alterations of sedimentary organic matter may potentially influence nutrient dynamics in lakes of northwestern China, thereby highlighting the importance of integrating suspended particle-associated photo-processes into nutrient management strategies for lakes.