Novel Protocol for Acute In Situ Ecotoxicity Test Using Native Crustaceans Applied to Groundwater Ecosystems

Current standardized laboratory test protocols use model species that have limitations to accurately assess native species responses to stressors. We developed and tested a novel acute in situ protocol for testing field-collected organisms. We used Asellus aquaticus and NaCl as a reference toxicant to test for the effects of location (laboratory vs. in situ), medium (synthetic vs. field water), substrate (presence vs. absence), and protocol replicability. We further tested the protocol using groundwater-adapted isopods: Proasellus assaforensis for the effect of location, P. cavaticus of medium and P. lusitanicus of substrate. Our results showed that A. aquaticus’ lethality obtained with the novel acute in situ protocol did not significantly differ from those from laboratory testing. However, laboratory tested P. assaforensis showed a higher sensitivity, suggesting that its acclimation to laboratory conditions might have pernicious effects. A. aquaticus and P. cavaticus showed a higher mortality using synthetic medium in situ and under laboratory conditions, which overestimated the stressor’s effect. Besides, substrate use had no significant effect. The novel acute in situ protocol allows the use of native species under realistic scenarios. It is particularly well adapted for assessing the risk of groundwater ecosystems but it can be applied to a wide range of ecosystems.info:eu-repo/semantics/publishedVersio

Laser-based techniques: Novel tools for the identification and characterization of aged microplastics with developed biofilm

Microplastics found in the environment are often covered with a biofilm, which makes their analysis difficult. Therefore, the biofilm is usually removed before analysis, which may affect the microplastic particles or lead to their loss during the procedure. In this work, we used laser-based analytical techniques and evaluated their performance in detecting, characterizing, and classifying pristine and aged microplastics with a developed biofilm. Five types of microplastics from different polymers were selected (polyamide, polyethylene, polyethylene terephthalate, polypropylene, and polyvinyl chloride) and aged under controlled conditions in freshwater and wastewater. The development of biofilm and the changes in the properties of the microplastic were evaluated. The pristine and aged microplastics were characterized by standard methods (e.g., optical and scanning electron microscopy, and Raman spectroscopy), and then laser-induced breakdown spectroscopy (LIBS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were used. The results show that LIBS could identify different types of plastics regardless of the ageing and major biotic elements of the biofilm layer. LA-ICP-MS showed a high sensitivity to metals, which can be used as markers for various plastics. In addition, LA-ICP-MS can be employed in studies to monitor the adsorption and desorption (leaching) of metals during the ageing of microplastics. The use of these laser-based analytical techniques was found to be beneficial in the study of environmentally relevant microplastics

Aquatic Biofilms—Sink or Source of Microplastics? A Critical Reflection on Current Knowledge

The scientific understanding regarding sources, occurrence, and effects of microplastics in the aquatic environment has advanced rapidly, leaving some meaningful knowledge gaps virtually untouched. One of them is the interactions of microplastics and biofilms, microbial communities ubiquitous in aquatic ecosystems and fundamental for a range of ecosystem‐level processes. It is evident that biofilms can quickly develop on the microplastic surface and consequently change particle properties and, as such, its fate and ecotoxicity. Moreover, microplastics interact with ubiquitous biofilms that are developed on any surfaces in aquatic ecosystems. Although the knowledge about these interactions is at best limited, it is expected that microplastics attach to the water–biofilm interface or penetrate the biofilm matrix. Microplastics can accumulate and ab‐ or adsorb to those biofilms where they are subjected to transformation processes such as fragmentation. Thus, biofilms may function as a sink. Changes in environmental conditions may, however, stress biofilms initiating their dieback and microplastic release, which could turn biofilms into a source of microplastics. We argue that the accumulation and release dynamics are a largely overlooked but potentially important piece to the puzzle that is a comprehensive understanding of microplastic fate in the environment and thus under the influence of multiple interacting factors. Environ Toxicol Chem 2022;41:838–843. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.Slovenian Research Agenc

Beyond ingestion

The interactions of microplastics with aquatic organisms have been studied primarily using animal species, with dietary ingestion being the most important uptake route. However, recent research indicated that microplastics also interact with biota via bioadhesion. This process has been studied in aquatic macrophytes under laboratory conditions where microplastics adhered to their biomass, but monitoring studies also confirmed that microplastic bioadhesion occurs in other species and in the natural environment. Similarly, microplastics adhere to microorganisms, and in the aquatic environment they can be retained by ubiquitous biofilms. This can occur on a natural substrate such as sediment or rocks, but biofilms are also responsible for enhanced bioadhesion of microplastics to other biotic surfaces such as plant surfaces. Adhesion to these large biotic surfaces could influence the abundance and bioavailability of microplastics in the environment. Only few studies have been conducted on the bioadhesion of microplastics to animals, but their results confirmed that bioadhesion may be even greater than particle ingestion by some animals, such as corals or bivalves. However, the ecotoxicological effects are not yet fully understood and the possible transport of microplastics, e.g. adhered to fish or aquatic insects, also needs to be considered. In summary, bioadhesion seems to be an important process for the interactions of microplastics and biota. Neglecting bioadhesion in an environmental context may limit our understanding of the behavior, fate, and effects of microplastics in the aquatic environment

Návrh marketingové strategie nábytkářské firmy

This diploma thesis deals with the design of markting strategy of the Brno company Resa, spol. s.r.o. The thesis is divided into two main parts. In theoretical part, there the main concepts relating to marketing are described by research form. These include marketing mix, marketing planning, communication, and a brief history od this issue. In the practical part, there the current state of selected company, the individual parts of the marketing plan and the results of the questionnaire survey are analyzed. From the findings subsequently proposal is based for innovation, or more precisely designing a new marketing strategy, which is the goal of the thesis

The first comprehensive study evaluating the ecotoxicity and biodegradability of water-soluble polymers used in personal care products and cosmetics

Water-soluble polymers (WSPs) are organic materials that have been used for decades in various applications as part of paints, coatings, adhesives, washing agents, pharmaceuticals, personal care products and cosmetics. However, their ecotoxicity, biodegradability, and overall impact on the environment are still unknown. In this study four polyacrylic acid- based WSPs (three in the solid state and one in the liquid state), which are widely used in cosmetic industry, were tested in terms of their ecotoxicity and biodegradability. The ecotoxicity tests were performed using aquatic plant Lemna minor, microalga Pseudokirchneriella subcapitata, crustacean Daphnia magna, bacterium Allivibrio fischeri, and a mixed bacterial culture of activated sludge (with heterotrophic and nitrifying microorganisms tested separately). All four WSPs had low or moderate effects on the tested organisms at several endpoints. However, the liquid WSP had a specific toxic effect on the bioluminescence of Allivibrio fischeri and the oxygen consumption of nitrifying microorganisms – 100 mg/L caused 73% and 88% inhibition, respectively. Therefore, some WSPs capable of inhibiting nitrifying microorganisms could have implications for the nitrification process in wastewater treatment plants and aquatic ecosystems, despite 100 mg/L being a high tested concentration and probably difficult to reach in wastewater. All investigated WSPs were not biodegradabletherefore, their persistence in the environment could be expected

Seeking for a perfect (non-spherical) microplastic particle

In recent decades, much attention has been paid to microplastic pollution, and research on microplastics has begun to grow exponentially. However, microplastics research still suffers from the lack of standardized protocols and methods for investigation of microplastics under laboratory conditions. Therefore, in this review, we summarize and critically discuss the results of 715 laboratory studies published on microplastics in the last five years to provide recommendations for future laboratory research. Analysis of the data revealed that the majority of microplastic particles used in laboratory studies are manufactured spheres of polystyrene ranging in size from 1 to 50 µm, that half of the studies did not characterize the particles used, and that a minority of studies used aged particles, investigated leaching of chemicals from microplastics, or used natural particles as a control. There is a large discrepancy between microplastics used in laboratory research and those found in the environment, and many laboratory studies suffer from a lack of environmental relevance and provide incomplete information on the microplastics used. We have summarized and discussed these issues and provided recommendations for future laboratory research on microplastics focusing on (i) microplastic selection, (ii) microplastic characterization, and (iii) test design of laboratory research on microplastics

The Response of Duckweed Lemna minor to Microplastics and Its Potential Use as a Bioindicator of Microplastic Pollution

Biomonitoring has become an indispensable tool for detecting various environmental pollutants, but microplastics have been greatly neglected in this context. They are currently monitored using multistep physico-chemical methods that are time-consuming and expensive, making the search for new monitoring options of great interest. In this context, the aim of this study was to investigate the possibility of using an aquatic macrophyte as a bioindicator of microplastic pollution in freshwaters. Therefore, the effects and adhesion of three types of microplastics (polyethylene microbeads, tire wear particles, and polyethylene terephthalate fibers) and two types of natural particles (wood dust and cellulose particles) to duckweed Lemna minor were investigated. The results showed that fibers and natural particles had no effect on the specific growth rate, chlorophyll a content, and root length of duckweed, while a significant reduction in the latter was observed when duckweed was exposed to microbeads and tire wear particles. The percentage of adhered particles was ten times higher for polyethylene microbeads than for other microplastics and natural particles, suggesting that the adhesion of polyethylene microbeads to duckweed is specific. Because the majority of microplastics in freshwaters are made of polyethylene, the use of duckweed for their biomonitoring could provide important information on microplastic pollution in freshwaters

Environmental aging and biodegradation of tire wear microplastics in the aquatic environment

Tire wear microplastics (TWM) are formed by friction between tires and road surfaces during driving and they belong among the most abundant microplastics in the environment. However, the information about their fate in the environment is still unknown. The aim of this study was to investigate the aging of TWM in freshwater under controlled laboratory conditions over 12 weeks. The development of biofilm, changes in physical properties and chemical composition, leaching and biodegradation of TWM were followed. The results showed colonization of the TWM surface by microorganisms (up to 45 mg/g), which, however, began to detach from the particles after eight weeks, reducing the amount of biofilm. TWM initially leached zinc and organic compounds (expressed as dissolved organic carbon - DOC), but their concentrations were low and decreased with time. The increase in DOC was observed after 10 weeks, possibly due to the decomposition of the biofilm and the release of organic matter. Aging resulted in changes of density of TWM, but the morphology and chemical composition of the TWM surface did not change. This confirms the results of the biodegradability tests, which showed no biodegradation within 12 weeks. Overall, the results indicated that TWM are not readily biodegradable and therefore may accumulate and persist in the aquatic environment