Statistical analysis and modelling of the manganese cycle in the subtropical Advancetown Lake, Australia

Abstract

Study region Advancetown Lake, South-East Queensland (Australia).

Study focus A detailed analysis of available meteorological, physical and chemical data (mostly coming from a vertical profiler remotely collecting data every 3 h) was performed in order to understand and model the manganese cycle. A one-dimensional model to calculate manganese vertical velocities was also developed.

New hydrological insights for the region The soluble manganese concentration in the hypolimnion is dominantly dependent on the dissolved oxygen level, pH and redox potential, which determine the speed of the biogeochemical reactions between different manganese oxidation states. In contrast, the manganese level in the epilimnion is mainly affected by the transport processes from the hypolimnion and thus to the strength of the thermal stratification, with high concentrations recorded solely during the winter lake circulation and wind playing only a minor role. The value of the peak concentration was found to be proportional to the amount of manganese in the hypolimnion and to the temperature of the water column at the beginning of the circulation period. In case of partial circulation only, a very high peak is espected during the next full winter turnover. This issue will increase in the future due to global warming and increased number of years with partial circulations only. These findings provide water authorities with increased manganese predictive power and thus proactive water treatment management strategies.