Assessment of macro-micro elements accumulation capabilities of Elodea nuttallii under gradient redox statuses with elevated NH4-N concentration

Abstract

Aquatic plants often encounter various redox conditions in their natural environment. Elodea nuttallii (Planch.), a submerged aquatic macrophyte, has a flexile ability to use different nutrient sources from various environments. In the present study, Elodea nuttallii was subjected to various redox conditions (+400 mV to –180 mV) at both normal (2.5 ppm) and high (10 ppm) ammonium concentrations and evaluated for macro and micro element accumulation. A reduced environment was prepared by adding glucose to growth medium and nitrogen gas bubbling, while an oxic environment was executed by atmospheric air bubbling. Plants in oxygen-deprived conditions manifested heavy metal (HM) toxicity, such as reduction of biomass and photosynthetic pigments, excess generation of reactive oxygen species (ROS), lipid peroxidation and reduction of major macro elements. In reduced treatments, the bioaccumulation sequence for micro elements was Cu>Mn>Zn>Al>Cd>Fe>Pb at both normal and high NH4-N concentrations. The combined effect of low redox state and high ammonium concentration had a strong physiological impact on the submerged macrophyte. However, macro- and micronutrient accumulation was more significantly affected by reduced environment than by a high NH4-N concentration