Browsing by Subject "microplastic"

Both microplastics (MPs, size 0.1 to 5 mm) and pharmaceuticals and personal care products (PPCPs) are ubiquitous in aquatic environments globally. Polystyrene microplastic (PS-MP) and diclofenac (DCF) are among the most widespread and commonly occurring MPs and PPCPs in the environment. Exposure to these chemicals in single has been reported to cause oxidative stress, immobilization, changes in growth and reproduction and even mortality in Daphnia magna. Moreover, MPs have the ability to act as a vector for PPCPs, and several laboratory studies have reported that PS-MP is able to absorb DCF. However, the combined toxicity of MPs and PPCPs remains largely unknown, especially as is the case for the combined toxicity of PS-MP and DCF in D. magna. In this study, D. magna was exposed to PS-MP and DCF, both in single and combined, at a concentration of 0.5 mg/L each. The aim was to assess the combined toxicity of the two, and determine whether they had a synergistic, additive, or antagonistic effect in D. magna. Whole organism endpoints monitored included mortality, immobilization, and moulting. Physiological endpoints monitored focused on oxidative stress and antioxidant defence, including reactive oxygen species (ROS), superoxidase dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST). The results indicated that both PS-MP and DCF in single were able to significantly alter D. magna antioxidant and biotransformation enzyme activities by inhibition of SOD and GST, while there were no observed impacts on the monitored whole organism endpoints or ROS and CAT. However, similar significant inhibition of SOD and GST was not observed in the combined exposure, which indicates that the combined toxicity of PS-MP and DCF in D. magna was most likely antagonistic. These results highlight that the combined toxicity of MPs and PPCPs is a complex topic that still needs further investigation to fully understand the complex interactions between MPs and PPCPs.

Microplastics are widely studied subject and have raised concern towards water security worldwide but the vector effect of microplastic has not yet fully understood. In this study the ability of microplastic to attach hydrophobic organic compounds is tested with a nonsteroidal anti-inflammatory drug diclofenac. The ability to attach hydrophobic organic compounds has been proved by microplastics but not with diclofenac. Diclofenac is also causing water security threats nearby wastewater treatment plants because it is biologically active and can cause stress to the aquatic organisms even in small quantities. The aim of this study is to see if microplastic has vector effect for the diclofenac. If microplastic retains diclofenac on its surface area it would decrease the stress factor effect of diclofenac towards the investigated macroalgae Aegagropila linnaei. The possible change of oxidative stress levels in A. linnaei is measured by peroxidase enzyme activity. The aim is to see if the enzyme activity raises or decreases when A. linnaei is exposed to microplastic with and without diclofenac. If the peroxidase enzyme activity decreases in macroalgae while exposing A. linnaei to both microplastic and diclofenac it would strengthen the vector effect hypothesis. As a result, the peroxidase enzyme activity seems to have a decreasing trend when the diclofenac concentrations increase. Diclofenac affected to peroxidase enzyme activity but microplastic does not show any signs of binding of diclofenac in this study, and therefore microplastic cannot act as a vector for diclofenac.

Aims and methods: Global plastic production is increasing annually and microplastics (MPs, particles of <5 mm in size) have been reported in the environment worldwide. In aquatic systems plastic pollution is present especially in coastal habitats, and MPs can concentrate within littoral zone vegetation. Numerous marine animals are known to be able to ingest MPs, and plastics can also have adverse effects on the health and behaviour of the exposed animals. This Master’s thesis examined trophic transfer of MPs in a Baltic Sea littoral food chain. Laboratory experiments with 10 µm fluorescence microspheres were conducted to study trophic transfer between food chains of different lengths. The longest food chain had three trophic levels: zooplankton, chameleon shrimp (Praunus flexuosus) and rockpool prawn (Palaemon elegans). Also, the gut passage time of rockpool prawn was experimentally studied. The digestive tracts of the studied animals were analysed for MPs under an epifluorescence microscope. Results: The results show that trophic transfer may be an important pathway of microplastic exposure for animals at higher trophic levels. The number of ingested microspheres in both chameleon shrimp and rockpool prawn was higher when the animals were exposed through pre-exposed prey in comparison to direct exposure from the water. In addition, the prawns ingested more MPs in the experiment with three trophic levels than in the two-level experiment. The results support earlier findings, that the feeding mode affects the microplastic exposure of animals. There were no clear results from the gut passage time experiment.