Temperature sensitivity of biodegradable dissolved organic carbon increases with elevating humification degree in subtropical rivers

Highlights: • The Q₁₀ values of BDOC were determined in the Three Gorges Reservoir river networks. • Approximately two-fold variations in Q₁₀ value of BDOC were observed. • Q₁₀ elevated with increasing humification degree, but decreased with increasing pH. • DOC quality and pH are powerful predictors of Q₁₀ of BDOC in subtropical rivers. • C quality-temperature hypothesis can be applied to BDOC in subtropical rivers. Biodegradable dissolved organic carbon (BDOC) plays a key role in C cycle in inland waters. However, the magnitude of temperature sensitivity (Q₁₀ value) of BDOC is still unclear, and the effect of DOC quality on Q₁₀ value of BDOC is not well verified in these aquatic systems. Here, we used a laboratory incubation experiment to determine the Q₁₀ value of BDOC in 57 rivers in the Three Gorges Reservoir area, China, and then tested whether C quality-temperature hypothesis could be applied to BDOC in inland waters. We observed approximately twofold variations in Q₁₀ values of BDOC (1.42–2.67) in these rivers. Moreover, the tight positive relationship between the Q₁₀ values of BDOC and DOC humification index indicated the applicability of C quality-temperature hypothesis in subtropical rivers. In addition, the Q₁₀ values of BDOC exhibited a negative relationship with pH. These findings suggest that DOC quality and pH are powerful predictors of temperature sensitivity of BDOC in subtropical rivers. In conclusion, our results would help to improve the C models and predict the feedback between climate warming and C dynamics in inland waters.