Optimization of aluminum treatment efficiency to control internal phosphorus loading in eutrophic lakes

Sammanfattning

Historical accumulation of phosphorus (P) in lake sediment often contributes to and sustains eutrophic conditions in lakes, even when external sources of P are reduced. The most cost-effective and commonly used method to restore the balance between P and P-binding metals in the sediment is aluminum (Al) treatment. The binding efficiency of Al, however, has varied greatly among treatments conducted over the past five decades, resulting in substantial differences in the amount of P bound per unit Al. We analyzed sediment from seven previously Al treated Swedish lakes to investigate factors controlling binding efficiency. In contrast to earlier work, lake morphology was negatively correlated to binding efficiency, meaning that binding efficiency was higher in lakes with steeply sloping bathymetry than in lakes with more gradually sloping bottoms. This was likely due to Al generally being added directly into the sediment, and not to the water column. Higher binding efficiencies were detected when Al was applied directly into the sediment, whereas the lowest binding efficiency was detected where Al was instead added to the water column. Al dose, mobile sediment P and lake morphology together explained 87% of the variation in binding efficiency among lakes where Al was added directly into the sediment. This led to the development of a model able to predict the optimal Al dose to maximize binding efficiency based on mobile sediment P mass and lake morphology. The predictive model can be used to evaluate cost-effectiveness and potential outcomes when planning Al-treatment using direct sediment application to restore water quality in eutrophic lakes.

Nyckelord

lake restoration; aluminium treatment; sediment injection; phosphorus; internal loading

Publicerad i

Water Research
2020, volym: 185, artikelnummer: 116150
Utgivare: Elsevier {BV}

SLU författare

• Agstam-Norlin, Oskar

  • Institutionen för vatten och miljö, Sveriges lantbruksuniversitet
    

• Lannergård, Emma

  • Institutionen för vatten och miljö, Sveriges lantbruksuniversitet
    

• Futter, Martyn

  • Institutionen för vatten och miljö, Sveriges lantbruksuniversitet
    

• Huser, Brian

  • Institutionen för vatten och miljö, Sveriges lantbruksuniversitet
    

UKÄ forskningsämne

Oceanografi, hydrologi, vattenresurser

Publikationens identifierare

• DOI: https://doi.org/10.1016/j.watres.2020.116150

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/108874