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

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 concentratio

Biodiversity in freshwaters: temporal trends and response to water chemistry (ICP Waters report 114/2013)

This report describes trends in biological diversity of benthic invertebrates from acid-sensitive lakes and rivers sampled between 1982 and 2011 in the Czech Republic, Germany, Latvia, Norway, Sweden and the UK. The results indicate an overall increase in species diversity during the study period, especially in the rivers. The increase in biodiversity is correlated with declining sulphate concentrations in surface waters, which in their turn are related to reduced atmospheric deposition of sulphur. The changes in biodiversity could be related chemical recovery of surface waters, where reduced sulphate concentrations are associated with increased pH and lowered aluminium concentrations. Apart from the increasing species diversity seen in most sites, the biological recovery trends varied among sites. As a consequence of increased species diversity, the aquatic ecosystems are likely to have a higher resilience against future threats. We can expect an analogous increase in species diversity for comparable sites elsewhere. The improved biodiversity in acid-sensitive waters is in contrast to the world-wide trend of decreasing freshwater species diversity. Our results suggest that international policies to reduce sulphur emissions have promoted a positive development in species diversity of invertebrates in acid-sensitive surface waters