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1.
Determination of organochlorine pesticides adsorbed on plastic pellets
2015, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: In the past years, several studies have revealed the presence of organic contaminants at concentrations from sub ng g–1 to mg g–1 on/in plastic pellets found in coastal environment worldwide [1,2,3]. Plastic pellets are actually industrial raw material, typically in the shape of small granules with a diameter of a few mm. They are categorized as microplastics (< 5 mm). They can be unintentionally lost in the environment during manufacturing and transport. They can subsequently reach the marine and coastal compartments. Due to their environmental persistence, they are widely distributed in the oceans and on beaches [1]. Organic pollutants associated to pellets are either additives (e.g. PBDEs) that are incorporated into plastics during production processes or hydrophobic chemicals (e.g. PCBs, organochlorine pesticides) which adsorb from the surrounding environment (e.g. seawater). Among these chemicals, some are recognized as POPs (Persistent Organic Pollutants) because of their persistence, bioaccumulation and potential adverse environmental and health effects. Thus, in order to better assess the impact of plastic pellets in coastal environment, it is necessary to determine the level of associated organic pollutants. The present study was carried out in the frame of DeFishGear project, which focuses on marine litter and microplastics issues in Adriatic region. This investigation aimed at developing an experimental protocol allowing the quantification of 11 organochlorine pesticides. Plastic pellets, sampled on beaches located in the Adriatic region, were first sorted by colour. Pesticides were extracted from the plastic matrix (c.a. 0.5 g) in a pressurized fluid extractor (50°C, 100 bar). Prior to evaporation, the extract was cleaned on Florisil sorbent through solid-phase extraction (SPE). The concentrated extracts were quantified on gas chromatography equipped with a micro electron capture detector (GC-μECD). Preliminary results revealed the presence of DDT transformation products.
Najdeno v: osebi
Ključne besede: organochlorine pesticides, microplastics, pellets, Adriatic region
Objavljeno: 15.02.2016; Ogledov: 2064; Prenosov: 0
.pdf Polno besedilo (3,92 MB)

2.
PHOTOLYSIS AND ECOTOXICITY OF THE ANTIBIOTIC CIPROFLOXACIN
Ketevan Neparidze, 2017, diplomsko delo

Opis: Over the last few decades, numerous pharmaceuticals coming from domestic sewage, livestock, hospitals and industries have been determined in ground, surface and drinking waters. A common example of these pollutants are fluoroquinolones, which are powerful antibiotics used in human and veterinary medicine. The presence of fluoroquinolones in the environment even at low concentration constitutes a threat to ecosystems and human health because they can lead to bacterial resistance issues. Up to now the environmental impacts of fluoroquinolones and their degradation products are not fully understood but it is known that they can negatively affect plants and aquatic organisms. In this study the degradation of ciprofloxacin (CIP) present in synthetic freshwater was investigated under simulated sunlight. Concentrations before and after degradation were determined using HPLC-DAD. The mineralisation rate of the treated solution was monitored on a total organic carbon analyser. The ecotoxicity of the initial samples and the degradation mixtures was assessed on organisms belonging to different trophic levels: a marine bacterium (Vibrio fischeri), a freshwater invertebrate (Daphnia magna) and seed clover (Trifolium repens). In parallel, the EC50 of CIP was determined for all organisms. The Vibrio fischeri and Trifolium repens tests showed that EC50 value was more than 250 mg/L and for Daphnia magna was 190 mg/L. Photolysis of CIP showed that after 90 min of irradiation, CIP was almost totally degraded (99%). Photolysis process of CIP led to the formation of toxic by-products towards Vibrio fischeri. The toxicity test results on Trifolium repens did not show significant difference between the control and the treated plants. Thus, CIP and its degradation products have no effect on the germination or root length of Trifolium repens. Tests on Daphnia magna after 240 min irradiation showed a 94% reduction of the toxic effect. Non-purgeable organic carbon (NPOC) analysis showed that there is no significant mineralisation of the sample even after 240 min of irradiation.
Najdeno v: osebi
Ključne besede: Key words: fluoroquinolones, ciprofloxacin, photolysis, toxicity tests, EC50 determination
Objavljeno: 31.01.2017; Ogledov: 2868; Prenosov: 209
.pdf Polno besedilo (947,78 KB)

3.
Analysis of polychlorinated biphenyls adsorbed on plastic pellets: Comparison of extraction techniques
Petra Makorič, 2017, magistrsko delo

Opis: Plastic resin pellets are one of the main components of plastic fragments in the marine environment. They are small granules, generally cylinder or disk-shaped, with a diameter of a few millimetres used as industrial raw material for the production of plastic manufactured items. Resin pellets can be unintentionally released to the environment during manufacturing and transport, and can reach the ocean through processes such as surface run-off. Because of their environmental persistence, they are widely distributed in the oceans and on the beaches, all over the globe. Plastic pellets are also a sink of toxic compounds such as polychlorinated biphenyls (PCBs) that are present in the environment. During this thesis, we designed a protocol for extracting and analysing PCBs from marine plastic resin pellets. Although pressurized fluid extraction (PFE) is not commonly used in the field of microplastics, it is a reliable and efficient technique applied in other research areas. Thus, this method was tested in this work. PCBs were extracted from plastic pellets with PFE at 65 ºC and under 100 bar with hexane. Then, the extracts were concentrated to 1 mL, cleaned up on Florisil cartridge through solid-phase extraction. Prior to analysis on GC-ECD, the cleaned extracts were concentrated again. In the second part of the thesis, the following four extraction techniques of PCBs from plastic resin pellets were compared: Soxhlet extraction, PFE, ultrasonication and maceration. The obtain results have shown that the best efficiency and repeatability of extraction is achieved with PFE. In case of Soxhlet extraction, the results were unrepeatable. Maceration and ultrasonication had 40-45 % lower extraction efficiencies than PFE.
Najdeno v: osebi
Ključne besede: PCB, plastic resin pellets, pressurized fluid extraction, Soxhlet, maceration, ultrasonication, microplastics
Objavljeno: 22.06.2017; Ogledov: 2412; Prenosov: 145
.pdf Polno besedilo (1,95 MB)

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