Simulation of the Contribution of Phosphorus-Containing Minerogenic Particles to Particulate Phosphorus Concentration in Cayuga Lake, New York

Gelda, Rakesh K.; Effler, Steven W.; Prestigiacomo, Anthony R.; Peng, Feng; Auer, Martin T.; Kuczynski, Anika; Chapra, Steven C.

Simulation of the Contribution of Phosphorus-Containing Minerogenic Particles to Particulate Phosphorus Concentration in Cayuga Lake, New York

2016

Phosphorus (P) associated with minerogenic particles delivered from watersheds can interfere with the common use of total P (TP) concentration as a trophic state metric in lacustrine systems, particularly proximate to tributary entries, because of its limited bioavailability. The concentration of unavailable minerogenic particulate P (PPₘ/ᵤ), where it is noteworthy, should be subtracted from TP in considering primary production potential and trophic state levels. A first mass balance model for PPₘ/ᵤ is developed and tested here for Cayuga Lake, New York. This is supported by a rare combination of detailed information for minerogenic particle level dynamics for the tributaries and lake, the bioavailability of tributary particulate P (PP), and previously tested hydrothermal/transport and minerogenic particle concentration submodels. The central roles of major runoff events and localized tributary loading at one end of the lake in driving patterns of PPₘ/ᵤ in time and space are well simulated, including (1) the higher PPₘ/ᵤ concentrations in a shallow area (“shelf”) adjoining the inputs, relative to pelagic waters, following runoff events, and (2) the positive dependence of the shelf increases on the magnitude of the event. The PPₘ/ᵤ component of P was largely responsible for the higher summer average TP on the shelf vs. pelagic waters and the exceedance of a TP water quality limit on the shelf. The effective simulation of PPₘ/ᵤ allows an appropriate adjustment of TP values to avoid overrepresentation of potential primary production levels.

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