Jakie zmiany w wodzie wywołują koagulanty i podwyższona temperatura podczas kiełkowania makrofitów?

Restoration treatments aim to improve water quality in aquatic ecosystems. One of the most commonly used methods is phosphorus inactivation with iron (Fe) coagulants. Furthermore, these management actions can be influenced, in turn, by the global climate change. Coagulants are considered harmless to aquatic organisms. However, there is a lack of research on how the changes in water variables, due to these compounds, might affect plant germination. Therefore, we conducted germination experiments with sediments from two small eutrophic aquatic ecosystems (within Albufera de Valencia Natural Park, Spain). To simulate the effect of global warming, the water in half of the containers was heated by 5 C (22 C and 27 C as experimental temperatures). Then Fe2(SO4)3 and FeCl3 coagulantus were added in concentration of ~4mg and ~11mg FeL-1. Fe was not added to the control. The laboratory experiment lasted two months. Variables such as pH, conductivity, oxygen content and chlorophyll a were measured before adding coagulants, on the experiment's 1th and 7th day, and then weekly. Chlorideand iron content were also measured on days 0, 1, 7, and 61, and iron concentration in the sediment at the end of the experiment. Germlings mainly of charophytes Chara vulgaris appeared after 7-14 days. Some chemical variables of the water initially changes after adding coagulants (e.g., pH decreased, iron content increased), but after 7 days, values of these variables were similar as in the controls. Time and temperature were the factors significantly influenced water variables. However, it should be remembered that reactions may be different depending on the seed bank and the sediment's features. Therefore, conducting germination tests before using coagulants as a restoration tool is highly recommended.
The research was fundedby the National Science Centre (Poland), MINIATURA 7, DEC-2023/07/X/NZ8/00711.