Assessment of the performance of evaporation suppressant films: Analysis and limitations of simple trialling methods

AbstractThe potential utility of monomolecular layers (“monolayers”) and other surface film materials for the reduction of open water evaporation has long been argued. However, outside the laboratory, trials to quantify the effectiveness of artificial surface films have produced highly variable results after application to water surfaces, whether natural water bodies or managed farm storages. This paper briefly reviews the physical mechanisms involved in evaporation suppression and the biophysical literature on aquatic surface microlayers. The wide-ranging results from 16 months of outdoor trough-scale and (simultaneous) replicated bucket-scale evaporation reduction trials are interpreted using biophysical measurements made on microlayer and immediate subsurface water samples taken from the experimental troughs. When the prevailing environmental conditions and other ancillary measurements are taken into account, plausible hypotheses arise to account for at least some of the observed trial-to-trial differe...