## 2 Results and Discussion
### Factors Influencing the T/O Compound Variation in the Eastern Drinking Water Source of Chaohu Lake
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Indexes** & **Factors** & **Geosmin** & **2-Methyl Isoborneol** & \(\beta\)**-Cyclocitral** & \(\beta\)**-Ionone** \\ \hline Biological & Chlorophyll-\(a\) & \(-0.133\) & \(0.300\) & \(0.206\) & \(0.095\) \\  & Cyanobacteria & \(-0.271\) & \(0.291\) & \(-0.013\) & \(0.052\) \\  & _Microcytsis_ spp. & \(-0.187\) & \(0.505\)\({}^{**}\) & \(-0.039\) & \(-0.121\) \\  & _Dolichospermum_ spp. & \(-0.418\)\({}^{*}\) & \(-0.350\)\({}^{*}\) & \(-0.087\) & \(0.387\)\({}^{*}\) \\ \hline Physical & Temperature & \(0.040\) & \(0.722\)\({}^{**}\) & \(-0.066\) & \(-0.132\) \\  & pH & \(0.230\) & \(0.413\)\({}^{*}\) & \(0.227\) & \(0.130\) \\  & Dissolved oxygen & \(0.004\) & \(-0.762\)\({}^{**}\) & \(0.069\) & \(0.253\) \\  & Conductivity & \(0.379\)\({}^{*}\) & \(0.788\)\({}^{**}\) & \(0.250\) & \(-0.022\) \\ \hline Nutrient & Total nitrogen & \(0.270\) & \(-0.010\) & \(-0.021\) & \(-0.071\) \\  & Nitrate & \(0.404\)\({}^{*}\) & \(0.298\) & \(-0.014\) & \(-0.166\) \\  & Ammonia nitrogen & \(0.322\) & \(0.372\)\({}^{*}\) & \(-0.025\) & \(-0.247\) \\  & Total phosphorus & \(-0.044\) & \(0.243\) & \(-0.096\) & \(-0.371\)\({}^{*}\) \\  & Orthophosphate & \(-0.210\) & \(-0.155\) & \(-0.202\) & \(-0.188\) \\ \hline Organic & Potassium permanganate index & \(0.210\) & \(0.452\)\({}^{**}\) & \(0.287\) & \(-0.030\) \\  & Dissolved organic carbon & \(0.028\) & \(0.383\)\({}^{*}\) & \(0.059\) & \(0.095\) \\ \hline \hline \end{tabular} Note: Correlation significance is denoted with \({}^{*}p<0.05\) or \({}^{**}p<0.01\).  
\end{table} 
Table 1: Correlation coefficients between T/O compounds and phytoplankton and physicochemical parameters from September 2011 to August 2012 in the eastern drinking water source of Chaohu Lake. Figure 2: Redundancy analysis (RDA) biplots showed the concentrations of dissolved and particulate T/O compounds in relation to the density of _Microcytsis_ spp. (Mic) and _Dolichosperm_ spp. (Dol) and the environmental factors, including water temperature (T), pH, dissolved oxygen, conductivity, TN, nitrate (NO\({}_{3}\)), nitrite, ammonia nitrogen, total phosphorus, and orthophosphate, in the eastern drinking water source of Chaohu Lake. d: dissolved T/O compounds; p: particulate T/O compounds. Relationships among T/O Compounds and Algal Toxins in the Eastern Drinking Water Source of Chaohu Lake  
Considering the frequent co-occurrence of T/O compounds with algal toxins in eutrophic lakes experiencing cyanobacterial blooms [11; 55], our investigation delved into the interrelationships among four T/O compounds and three prevalent microcystin (MC) variants, namely MC-LR, MC-RR, and MC-YR (Table 2). Positive correlations were observed among the three T/O compounds--GSM, CYC, and ION--suggesting a potential co-occurrence or similar influencing factors for these compounds. However, it is noteworthy that an inverse association was identified between GSM and MC-YR, indicating a contrasting relationship between these specific T/O and MC variants. Interestingly, no significant correlations were found between the other microcystin variants (MC-LR and MC-RR) and the examined T/O compounds. This suggests a complex and nuanced relationship between T/O compounds and specific microcystin variants, with potential variations in their production or dynamics. These findings contribute to our understanding of the interactions between T/O compounds and microcystins in eutrophic lakes during cyanobacterial blooms. The absence of correlations with certain microcystin variants suggests distinct regulatory mechanisms or factors influencing their dynamics.