Acceleration of Phosphorus Flux from Anoxic Sediments in a Warming Lake Erie

Harmful Algal Blooms (HABs) have been detrimental to the health of the Western Basin of Lake Erie (WBLE) and the safety of drinking water for surrounding communities for over a decade. Nutrient inputs have exacerbated these problems by promoting HAB growth. While external nutrient loading is being addressed, more needs to be discovered about the potential for internal loading from lake sediments. Anoxic sediments release phosphorus into overlying waters at increasing rates that correlate with increasing temperature, particularly between 20 ℃ and 30 ℃. (Gibbons and Bridgeman, 2020). However, the trajectory of the increase in release is undetermined. In this study, sediment cores were collected and incubated in anoxic conditions at varying temperatures within the range of 20 ℃ and 30 ℃. Results from these incubations showed the largest increase in phosphorus flux for site 4P occurred between the temperatures of 26 ℃ and 29 ℃ (average concentration increase of 100.9 µg/L). However, site 7M showed the largest increase in phosphorus flux between 23 ℃ and 26 ℃ (average concentration increase of 252.4 µg/L). Such a large flux in this temperature range is alarming as lake bottom temperatures already exceed 23 ℃ and are likely to increase in the future.