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Iron overload consequences for submerged plants stoichiometry, homeostasis and performance
AbstractAccelerated 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.
Hidden effects of aluminum coagulant on freshwater mussels: Responses of Anodonta anatina and Unio tumidus to lake restoration
The Influence of Water Conditions on Heavy Metal Tolerance Mechanisms in Hybrid Poplar (Populus nigra × Populus maximowiczii) in the Light of Sustainable Development Goals
Sustainable management of soils degraded by heavy metals is a major environmental challenge. The aim of this study was to evaluate the acclimatization ability of the hybrid Populus nigra L. × Populus maximowiczii under variable soil moisture conditions. In a greenhouse experiment, it was shown that both soil moisture level and the presence of metals significantly affected plant growth and metabolism. The hybrid showed high nickel (Ni) accumulation at low and medium soil moisture content (LMC, MMC) (BCF 4.56 and 4.99), while copper (Cu) accumulation was highest at MMC (BCF 5.53). Nickel translocation to aerial parts increased after exposure (TF up to 0.63), while Cu translocation was limited (TF below 0.94). Increased humidity promoted the biosynthesis of low molecular weight organic acids (LMWOAs) in roots, with the highest total content recorded in the Cu treatment under high soil moisture content (HMC) (230 μg g−1 FW). In the stems, the highest levels of sum LMWOAs were found under HMC conditions (6764 μg g−1 FW in the control sample), while among the phenolic acids, the highest content of chlorogenic acid (~144 μg g−1 FW) was determined under LMC conditions under Ni stress, which indicates a strong defense response of the plant. The obtained results emphasize the importance of selecting appropriate water conditions in remediation strategies and indicate that the tested poplar hybrid may be a promising tool in improving the quality of degraded soils.
The Effect of Salinity on Heavy Metal Tolerance in Two Energy Willow Varieties
This study evaluated the response of two willow varieties, Salix × smithiana Willd. and Salix viminalis L. var. Gigantea, to selected heavy metals and elevated soil salinity, simulating complex environmental conditions during phytoremediation. Plants propagated from stem cuttings were cultivated in pots under field conditions in soil artificially contaminated with a mixture of Cd, Ni, Cu, Zn, and Pb salts at two concentration levels representing lower and higher guideline thresholds. Sodium chloride was added to induce salinity stress. S. × smithiana exhibited enhanced growth under combined metal and salinity stress, suggesting efficient tolerance mechanisms. This was reflected in elevated relative water content (RWC) and increased accumulation of Zn and Cd in shoots. In contrast, Gigantea showed growth inhibition and primarily sequestered metals in roots, indicating a stress-avoidance strategy and reduced metal translocation. While salinity alone negatively affected both varieties, its combination with metals mitigated growth reduction in S. × smithiana, possibly due to improved ion homeostasis or cross-tolerance. Zn and Cd displayed the highest bioconcentration and mobility. Based on bioconcentration factor (BCF) and translocation factor (TF), S. × smithiana appears suitable for phytoextraction, whereas S. viminalis var. Gigantea appears suitable for phytostabilization. These results support species-specific approaches to phytoremediation in multi-contaminant environments.
Drought Differently Modifies Tolerance and Metal Uptake in Zn- or Cu-Treated Male and Female Salix × fragilis L.
The aim of this study was to determine the tolerance to metals (Zn, Cu) and drought of male and female Salix × fragilis L. under isolated and combined treatments, and to assess the metal uptake and profiling of metabolic plant responses. The 14-day experiment was performed in a hydroponic system, and metals were applied at 1.5 mM in a Knop’s solution. Drought simulation was achieved by adding sorbitol at a moderate level (200 mM). Isolated Zn treatment enhanced plant growth, more pronouncedly in females. Equimolar Cu treatment caused diverse reactions, and females exhibited significantly higher tolerance. Male specimens were less tolerant to isolated drought and to combined drought and metal presence. The highest contents of Cu and Zn were found in roots, compared to the aboveground tissues (wooden rods and leaves), of both female and male metal-treated plants. Simultaneously applied drought limited Zn accumulation in roots and elevated its translocation to leaves while increasing Cu accumulation, predominantly in females showing higher tolerance. Both isolated and combined drought and metals reduced leaf water content, caused the allocation of mineral nutrients (Ca, Mg, K, and Na), and affected metabolism in a stressor-specific and sex-dependent manner. For males, Cu accumulation in the leaves was significantly correlated with the majority of metabolites, while for both sexes, kaempferol and salicylic acid were strongly correlated, indicating their role in tolerance against the metal. The obtained results are an excellent starting point for the practical use of male and female Salix × fragilis L. in areas heavily polluted with Cu or Zn and exposed to drought, for the purpose of their recultivation.
Metal Accumulation and Tolerance of Energy Willow to Copper and Nickel under Simulated Drought Conditions
The aim of this study was to determine the effect of drought on the accumulation and tolerance of energy willow (Salix viminalis L. var. ‘Gigantea’) to copper (Cu) and nickel (Ni) in the context of phytoremediation potential of the plant and biomass production under adverse water conditions. Drought was simulated with polyethylene glycol (PEG-6000. 5%), and metals were added at a concentration of 1 mM. Plants were cultivated in greenhouse conditions for 21 days according to the experimental variants: control, Cu, Ni, PEG, PEG + Cu and PEG + Ni. The results indicate high toxicity of Cu (chlorosis, necrosis, decrease in biomass, plant dehydration, increase in the content of proline and phenolic compounds), and PEG + Cu co-treatment increased the toxicity of the metal. Ni applied at the same concentration did not cause toxicity symptoms. The willow exhibits the ability to accumulate Ni, and mutual application of PEG + Ni increased Ni uptake to new shoots. Cu caused elevated accumulation of proline and phenolics in leaves accompanied with a decreased carbon and nitrogen content in roots in favor of young shoots. Both metals and drought led to disruption in the content of mineral nutrients (Ca, Mg, Fe). Due to high tolerance to Ni and drought, S. viminalis var. ‘Gigantea’ bears high potential for biomass production on Ni-polluted sites with accompanying metal uptake increased under water deficit.