Internal loading of phosphorus in western Lake Erie

This study applied eight techniques to obtain estimates of the diffusive flux of phosphorus (P) from bottom sediments throughout the western basin of Lake Erie. The flux was quantified from both aerobic and anaerobic incubations of whole cores; by monitoring the water encapsulated in bottom chambers...

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Bibliographic Details
Published in:	Journal of Great Lakes research Vol. 42; no. 4; pp. 775 - 788
Main Authors:	Matisoff, Gerald, Kaltenberg, Eliza M., Steely, Rebecca L., Hummel, Stephanie K., Seo, Jinyu, Gibbons, Kenneth J., Bridgeman, Thomas B., Seo, Youngwoo, Behbahani, Mohsen, James, William F., Johnson, Laura T., Doan, Phuong, Dittrich, Maria, Evans, Mary Anne, Chaffin, Justin D.
Format:	Journal Article
Language:	English
Published:	Elsevier B.V 01-08-2016
Subjects:	Internal loading Lake Erie Phosphorus Phosphorus flux Sediments Western Basin Lake Erie Phosphorus Internal loading Phosphorus flux Western Basin Sediments
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Summary:	This study applied eight techniques to obtain estimates of the diffusive flux of phosphorus (P) from bottom sediments throughout the western basin of Lake Erie. The flux was quantified from both aerobic and anaerobic incubations of whole cores; by monitoring the water encapsulated in bottom chambers; from pore water concentration profiles measured with a phosphate microelectrode, a diffusive equilibrium in thin films (DET) hydrogel, and expressed pore waters; and from mass balance and biogeochemical diagenetic models. Fluxes under aerobic conditions at summertime temperatures averaged 1.35mg P/m2/day and displayed spatial variability on scales as small as a centimeter. Using two different temperature correction factors, the flux was adjusted to mean annual temperature yielding average annual fluxes of 0.43–0.91mg P/m2/day and a western basin-wide total of 378–808Mg P/year as the diffusive flux from sediments. This is 3–7% of the 11,000Mg P/year International Joint Commission (IJC) target load for phosphorus delivery to Lake Erie from external sources. Using these average aerobic fluxes, the sediment contributes 3.0–6.3μg P/L as a background internal contribution that represents 20–42% of the IJC Target Concentration of 15μg P/L for the western basin. The implication is that this internal diffusive recycling of P is unlikely to trigger cyanobacterial blooms by itself but is sufficiently large to cause blooms when combined with external loads. This background flux may be also responsible for delayed response of the lake to any decrease in the external loading.
ISSN:	0380-1330
DOI:	10.1016/j.jglr.2016.04.004