Kinetic and equilibrium analysis of penguin guano trace elements release to Antarctic seawater and snow meltwater

The present work extends the scope of prior studies through analysis, modelling and simulation of the As, Cd, Co, Cu, Fe Mn, Mo, Ni and Zn release from Gentoo (Pygoscelis papua) and Chinstrap (Pygoscelis antarcticus) penguin guano to the Southern Ocean seawater and to Antarctic snow meltwater. Laboratory experimental results have been modelled considering kinetic processes between water and guano using two element pools in the guano compartment; its application allows us to interpret behaviours and predict release concentrations of dissolved trace elements from guano which are potentially useful for incorporation as elements source into biogeochemical models applied in the Southern Ocean. Variations in quantities and release patterns depending on the type of guano and aqueous medium in contact have been identified. The release percentages from the guano to the aqueous medium, once the steady state has been reached, vary depending on the water medium and guano type in the ranges of 100–2.9 % for Mo; 91.5–68.6 % for Ni; 81.8–22.8 % As; 52.0–43.9 % Cu; 26.9–7.4 % Mn; 24.9–5.4 for Co; 4.4–3.2 % for Zn and 0.94–0.51 % for Fe. Considering a penguin population of 774,000 Gentoo and 8,000,000 Chinstrap, the estimated annual mass released to the both seawater and freshwater would be ≈18,500 kg for Cu, ≈1710 kg for Zn, ≈1944 kg for Fe, ≈1640 kg for Mn, ≈499 kg for As, ≈289 kg for Ni, ≈155 kg for Mo, ≈36.7 kg for Cd and ≈8.1 kg for Co. These contributions can be locally significant both in promoting phytoplankton growth and in their role as inhibitors of primary productivity. [Display omitted] •Guano contains leachable elements that are locally important for primary production.•Released concentrations can be useful to feed Southern Ocean biogeochemical models.•Kinetic release is modelled considering two pools in penguin guano compartment.•Similar release % to sea- and snow-water are observed in both penguin species.•Total estimated kg/yr released in the order Cu> > Zn > Fe ≈ Mn > As> > Ni > Mo> > Cd > Co.