Analysis of the causes and mechanisms of 2-MIB concentration variation in Danjiangkou Reservoir

To strengthen the water safety guarantee of Danjiangkou Reservoir, with the data of algal monitoring in the reservoir from Jul. to Oct. in 2025, the concentration variation characteristics and causes of 2-MIB in Danjiangkou Reservoir were analyzed. the paper shows that: (1)There is a significant synchronization between 2-MIB and AD in Danjiangkou Reservoir in terms of temporal variation. During the peak period of algal proliferation (August-September), both reached obvious peaks. The peak 2-MIB concentration was nearly 30ng/L in the center of the Dan Reservoir, nearly 45ng/L at 0+900m downstream of the dam, nearly 35ng/L at Taicha Regional Boundary Station, and nearly 25ng/L at Liangshuihe-Taizishan. AD showed a similar spatial gradient.(2)The distribution of 2-MIB is jointly driven by "water quality-biological factors from direct algal metabolism" and "basic factors of nutrients-habitat". 2-MIB is highly correlated with factors such as algae, water temperature, pH, organic matter, and nutrients, among which the correlations with Chla, TN, WT, pH and EC are particularly significant.