Abstract:Particle organic carbon (POC) in riverine systems is a critical component in the global carbon cycle, and it could provide information on human activities in particular land use in their representative drainage areas. In present study, soil and plant in the riparian zone and algae and POC in river waters were sampled in the Jinshui River Basin. Stable carbon isotopes analysis and elemental C/N ratios measure were applied to investigate the seasonal change of concentration, sources and their contributions of POC in river. The results showed that the POC concentration in river had remarked seasonal variations in the Jinshui River, in a decrease order of summer, spring, autumn, and winter. Larger quantity of soil organic matters and plant debris were washed into the river in spring and summer due to intensive rainfalls, and higher temperature was in favor of algal growing and which could produce more endogenous POC. Additionally, the POC concentration in slightly disturbed zone (i.e., upstreams) was obviously lower than that of moderately disturbed zone and intensely disturbed zone (i.e., middle reach and downstreams). These showed that seasonal change and human disturbance such as change of land use had a great influence on the concentration of POC in the Jinshui River. Qualitative analysis using stable carbon isotope (δ13C), elemental C/N ratios and the relational graph indicated that the major sources of POC in river were soil organic matter, C3 plants, and algae, and contribution from plankton and C4 plants were minimal. Ternary analysis model further revealed tempo-spatial variabilities of the sources and their contribution of POC in river. The results showed that the sources and their contribution of POC in river had remarked seasonal variations in the Jinshui River. But, the contribution of POC in river from endogenous (i.e., algae) was obviously lower than that from exogenous (i.e., soil organic matter and C3 plants).At the same time, the sources and their contribution of POC in river also showed differences between different zones. The POC in slightly disturbed zone and in moderately disturbed zone (i.e., upstreams and middle reach) mainly came from soil organic matter and C3 plants, and they were soil organic matter and algae in intensely disturbed zone (e.g., downstream). Therefore, human disturbance had a great influence on the sources and their contribution of POC in the Jinshui River.