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

To strengthen the water quality safety guarantee of the Danjiangkou Reservoir, the variation characteristics of 2-methylisoborneol (2-MIB) concentrations and their driving factors were analyzed based on algal monitoring data throughout 2025. The results indicated that: ① 2-MIB concentrations were significantly synchronized with total algal density(AD) over time. During the intensive algal proliferation period (August~September), both variables exhibited pronounced peaks, with maximum 2-MIB levels approaching 30 ng/L in the central area of the Danjiang sub-reservoir, 45 ng/L at the 0+900 monitoring site downstream of the dam, 35 ng /L at the Taocha Boundary Station, and 25 ng/L in the Liangshuihe-Taizishan section. AD displayed a similar spatial gradient. ② The distribution of 2-MIB was jointly driven by two groups of factors: water quality and biological factors directly related to algal metabolism, basic factors associated with nutrients and habitat conditions. 2-MIB was highly correlated with algal, water temperature(WT), pH, organic matter and nutrients, with particularly significant relationships observed for chlorophyll-a(Chla), total nitrogen(TN), WT, pH and electrical conductivity(EC). Operational measures such as aeration and ultrasonic algal control could regulate the release process of 2-MIB.