Rivers are major conduits for carbon (C) transport from terrestrial reservoirs to the oceans and atmosphere. Understanding C dynamics  in the riverine ecosystem has become increasingly important for understanding global carbon cycle. 

A research group led by Prof. ZHANG Quanfa from Wuhan Botanical Garden investigated the seasonal and spatial variations in C concentrations and their carbon isotopic signatures, as well as their controlling factors in the tributaries and main channel of the upper Han River, China.  

Particulate organic carbon (POC) concentration was significantly higher in wet season in main channel. Dissolved inorganic carbon (DIC) and POC were both positively related to Dissolved organic carbon (DOC), and positively correlated with water temperature and total suspended solid (TSS), respectively.    

The carbon isotopic signatures, δ¹³C-DIC and δ¹³C-POC, had significant seasonal and spatial variations. δ¹³C-DIC was significantly higher in dry season and negatively related to the TSS concentration, while, δ¹³C-POC was significantly higher in the tributaries in dry season and negatively correlated with water temperature, DIC, and DOC concentrations.   

Results suggest that water temperature and TSS are the primary factors in regulating concentrations, and their stable isotopic signatures are primarily affected by aquatic photosynthesis and riverine respiration in the upper Han River, China.    

Research was funded by the National Natural Science Foundation of China. Results were published in Environmental Science and Pollution Research entitled “Carbon concentrations and their stable isotopic signatures in the upper Han River, China”.