Eliška Maršálková

Multimodal Action and Selective Toxicity of Zerovalent Iron Nanoparticles against Cyanobacteria

Cyanobacteria pose a serious threat to water resources around the world. This is compounded by the fact that they are extremely resilient, having evolved numerous protective mechanisms to ensure their dominant position in their ecosystem. We show that treatment with nanoparticles of zerovalent iron (nZVI) is an effective and environmentally benign method for destroying and preventing the formation of cyanobacterial water blooms. The nanoparticles have multiple modes of action, including the removal of bioavailable phosphorus, the destruction of cyanobacterial cells, and the immobilization of microcystins, preventing their release into the water column. Ecotoxicological experiments showed that nZVI is a highly selective agent, having an EC(50) of 50 mg/L against cyanobacteria; this is 20-100 times lower than its EC(50) for algae, daphnids, water plants, and fishes. The primary product of nZVI treatment is nontoxic and highly aggregated Fe(OH)(3), which promotes flocculation and gradual settling of the decomposed cyanobacterial biomass.

Organic flocculants for the removal of phytoplankton biomass

The formation of noxious phytoplankton blooms causes deterioration of water quality in aquaculture ponds and reservoirs, but also in swimming pools and aquaria. We have studied the effects of selected cationic polyacrylamides on natural phytoplankton community, which was investigated by a decrease of chlorophyll a content in the water column and photosynthetic activity of phytoplankton floccules. Results indicate that cationic polyacrylamides are able to remove more than 80% of phytoplankton biomass. Moreover, no cell damage or lysis was observed by microscopic observation after flocculation. To our knowledge, this is the first report suggesting the removal of cyanobacterial blooms by organic flocculants. Cationic polyacrylamides are biodegradable organic flocculants with low toxicity to aquatic organisms, and seem to be a prospective tool with a possibility for algal or cyanobacterial bloom management in aquaculture.

Observation of Biological Pests on Building Facades by Thermocamera

Microorganisms on the facades of buildings (eg, algae and cyanobacteria) are the harmful factors that cause destruction of the surface of building materials in exterior (facade paints, plasters, masonry, stone, concrete, etc.). One of the properties of listed biological factors is the production of thermal energy, which can vary in different species. Mentioned energy can be recorded using infrared thermography. The paper contains the results of the examined expressions of the biological pests on the insulated facades of the buildings using infrared thermography.