Iron overload consequences for submerged plants stoichiometry, homeostasis and performance

Abstract

Accelerated lakes eutrophication is one of the greatest challenges nowadays. To counteract its negative effects, large-scale restoration treatments are carried out worldwide. However, research in this field is mainly focused on the process effectiveness and there is a scarcity of studies concerning the impact of restoration treatments on water organisms and ecosystem homeostatsis. Our microcosm study presents the effects of a phosphorus coagulant (iron [III] chloride) on functional traits changes, oxidative stress and macro- and microelement stoichiometry disturbances in macrophyte Myriophyllum spicatum, a model species inhabiting eutrophic waters. Application of the coagulant to experimental vessels influenced the physicochemical and optical parameters of water and led to significant changes in biogeochemistry. Stoichiometric alterations were reflected by disturbances in the relative contents of macro- (C, N, P, Ca, Mg) and microelements (Fe, Zn, Cu, Co) and induced luxury consumption of available ions. Physicochemical and stoichiometric changes mutually exerted negative influence on M. spicatum functional traits. The parameters of oxidative stress remained at low levels, comparable to the untreated control whereas stoichiometric analysis revealed the activation of mechanisms responsible for minimizing low light stress. The ability of M. spicatum to maintain homeostasis of Cu and Co under simulated chemical water restoration was closely related to high concentrations of Fe and Zn ions, which simultaneously were not subjected to homeostasis control. Thus, chemical lake restoration treatments based on phosphorus coagulants are not as environmentally safe as previously considered and may have far-reaching consequences for the biogeochemical cycle and food web functioning.

Combining Multiple Remediation Techniques Is Effective for the Remediation of Eutrophic Flowing Water

“…Adsorbent in situ inactivation is a common means of chemical remediation that can inhibit sediment P release by adding P adsorbent materials containing elements such as lanthanum, aluminum, iron, or calcium [11][12][13][14]. However, adsorbents may pose problems such as secondary contamination and unstable effects [15][16][17]. Phytoremediation can stabilize water quality and improve the biodiversity of water.…”

“…The P adsorbent used in most studies is lanthanum-modified bentonite (Phoslock ® ). Because lanthanum is a rare-earth element with scarce resources and potential biological toxicity [25,26], this study used calcium, which is widely available, eco-friendly, and can be effective in the removal of phosphorus [16,17], as a P removal material. However, the direct use of calcium-based compounds often causes large changes in water pH, and the dosing method also affects treatment longevity [27].…”