Internal loading of phosphate in Lake Erie Central Basin

Adina Paytan, Kathryn Roberts, Sue Watson, Sara Peek, Pei Chuan Chuang, Delphine Defforey, Carol Kendall

Research output: Contribution to journalArticlepeer-review

123 Scopus citations

Abstract

After significant reductions in external phosphorus (P) loads, and subsequent water quality improvements in the early 1980s, the water quality of Lake Erie has declined considerably over the past decade. The frequency and magnitude of harmful algal blooms (primarily in the western basin) and the extent of hypoxic bottom waters in the central basin have increased. The decline in ecosystem health, despite meeting goals for external P loads, has sparked a renewed effort to understand P cycling in the lake. We use pore-water P concentration profiles and sediment cores incubation experiments to quantify the P flux from Lake Erie central basin sediments. In addition, the oxygen isotopes of phosphate were investigated to assess the isotopic signature of sedimentary phosphate inputs relative to the isotopic signature of phosphate in lake water. Extrapolating the total P sediment flux based on the pore-water profiles to the whole area of the central basin ranged from 300 to 1250 metric tons per year and using the flux based on core incubation experiments an annual flux of roughly 2400 metric tons of P is calculated. These estimates amount to 8–20% of the total external input of P to Lake Erie. The isotopic signature of phosphate in the extractable fraction of the sediments (~ 18‰) can explain the non-equilibrium isotope values of dissolved phosphate in the deep water of the central basin of Lake Erie, and this is consistent with sediments as an important internal source of P in the Lake.

Original languageEnglish
Pages (from-to)1356-1365
Number of pages10
JournalScience of the Total Environment
Volume579
DOIs
StatePublished - 1 Feb 2017
Externally publishedYes

Keywords

  • Lake Erie
  • Oxygen isotopes of phosphate
  • Phosphorus flux
  • Sediments

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

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