Wettability of Biofouled Submerged Substrata: Exploratory Relationships with Freshwater Environmental Characteristics

This study investigates the wetting behavior of artificial substrates: polymers, metals, and glass, and natural freshwater-submerged substrata represented by Potamogeton lucens leaves, collected from shallow eutrophic lakes in northern Poland. Surface interactions were quantified by contact angle measurements and interpreted using the dynamic contact angle hysteresis formalism, with particular emphasis on the apparent surface free energy γ_SV, its polar and dispersive components, adhesive spreading pressure Π, work of adhesion W_A, and spreading W_S. These parameters characterize substrate-specific surface differences associated with aging and biofouling. Contact angles were measured using a previously developed captive bubble system, enabling the characterization of fully hydrated, heterogeneous submerged surfaces. Potential relationships between selected lake water characteristics and macrophyte surface wettability parameters were explored using Spearman's rank correlation. Measurements of young and old leaves from three lakes revealed consistent age-associated changes in advancing contact angle and apparent surface energetic parameters. Exploratory analysis revealed potential relationships between the advancing contact angle and Secchi depth in both leaf-age groups, as well as between age-associated changes in wettability and ammonium concentration or conductivity. The results suggest that wettability analysis may help characterize submerged surface conditions and identify environmental relationships that warrant further investigation.