Sammanfattning

Estimating air-water gas transfer velocities (k) is integral to understand biogeochemical and ecological processes in aquatic systems. In lakes, k is commonly predicted using wind-based empirical models, however, their predictive performance under conditions that differ from their original calibration remains largely unassessed. Here, we collected 2222 published k estimates derived from various methods in 46 globally distributed lakes to (1) evaluate the predictions of a selection of six available wind-speed based k models for lakes and (2) explore and develop new empirical models to predict k over global lakes. We found that selected k models generally performed poorly in predicting k in lakes. Model predictions were more accurate than simply assuming a mean k in only 2-39% of all lakes, however, we could not identify with confidence the specific conditions in which some models outperformed others. We developed new wind-based models in which additional variables describing the spatial coverage of k estimates and the lake size and shape had a significant effect on the wind speed-k relationship. Although these new models did not fit the global dataset significantly better than previous k models, they generate overall less biased predictions for global lakes. We further provide explicit estimates of prediction errors that integrate methodological and lake-specific uncertainties. Our results highlight the potential limits when using wind-based models to predict k across lakes and urge scientists to properly account for prediction errors, or measure k directly in the field whenever possible.

Nyckelord

Air-water gas exchange; Model assessment; Lake gas flux; Wind speed; k(600); Reaeration

Publicerad i

Aquatic Sciences - Research Across Boundaries
2020, Volym: 82, nummer: 3, artikelnummer: 53
Utgivare: SPRINGER BASEL AG

SLU författare

• Klaus, Marcus

  • Institutionen för skogens ekologi och skötsel, Sveriges lantbruksuniversitet
    
  • Umeå Universitet

UKÄ forskningsämne

Oceanografi, hydrologi, vattenresurser


Publikationens identifierare

DOI: https://doi.org/10.1007/s00027-020-00729-9

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/105608