Postdoctoral and Research Associate Seminar Series: Zahra Akbarzadeh

Phosphorus Dynamics in Lake Erie's littoral zone: Insights from a regionalized mass balance mode

Eutrophication is a major problem in the nearshore areas of large lakes. The nearshore areas are the primary recipients of nutrient loading from their watersheds. Furthermore, they act as biogeochemical reactors that can strongly affect the in-lake fate and transport of the nutrient elements delivered to the lake. In this seminar, I will discuss our research centered on phosphorus (P) dynamics within the littoral zone of Lake Erie. I will present the results from our regionalized mass balance model developed for Lake Erie in which the lake is divided into multiple nearshore and offshore compartments. The model represents the dissolved (DP) and particulate (PP) fractions of total P (TP) in the water column, plus TP in the bottom sediments. The mean annual P loadings from land and atmosphere (2003-2016), along with the mean annual water fluxes between the different lake compartments were imposed to the model. Special attention has been given to estimating the littoral-offshore water exchange fluxes because little is known about how these affect the whole P cycling. Overall, our results highlight the role of littoral zone processes in shaping the lake's phosphorus budget. Additionally, we carried out model simulations to analyze the effect of changes in water circulation on the littoral-offshore P exchanges. Such changes may help explain why, in contrast to the shallow littoral areas, deeper offshore areas of Lake Erie may be experiencing declining primary productivity.