Seasonal variation and geographical distribution of 1,4-dioxane in surface waters and wastewaters in Tallahassee, Florida, USA.

This research investigated the effects of seasonal variation and geographical distribution on 1,4-dioxane concentrations in four lakes and a wastewater treatment plant (WWTP) in Florida, USA. The results showed significant seasonal variation, with the highest 1,4-dioxane concentrations detected during spring and the lowest during summer in both surface water and wastewater. Regression analyses revealed that 1,4-dioxane concentrations were negatively correlated with both water temperature and precipitation, suggesting that hot and wet conditions favored relatively lower dioxane concentrations because of dilution. Spatially, the lake with the highest concentration (Lake Talquin) was associated with a large mixed-use watershed and long residence time, whereas the lake with the lowest concentration had limited connectivity and fewer potential contamination sources. Hurricanes had immediate impacts on the 1,4-dioxane concentrations in lakes. However, the impacts varied from lake to lake, depending on the balance between increased 1,4-dioxane input and runoff dilution. The highest wastewater concentration was measured in the tertiary effluent, which may be attributed to in-situ formation through oxidation of 1,4-dioxane precursors during chlorination. Statistical analyses indicated significant seasonal, spatial, and treatment-stage effects (p < 0.05).