Academic literature on the topic 'Polystyrene microplastics'

Plastic debris are accumulating in our oceans and are degraded into smaller pieces which eventually becomes small enough to be available to lower thropic level organisms. Microplastics, commonly defined as plastic particles <5 mm, are globally distributed and found at remote locations far away from industrialized and populated areas. The effects of macro sized plastics is well understood whilst the effects of microplastics is hard to predict. It is known that microplastics act as transfer vectors for a wide range of toxic chemicals into organisms, and it is also known that the particle itself can cause toxic responses such as increased immune response and endocrine disruption. Researchers utilize virgin plastic pellets in order to determine the toxicological effect of the plastic particle itself, but resent research suggest that these virgin plastics may release chemicals that contribute to the toxic response and thus complicates the interpretation of the results. In present study, five different virgin plastics were allowed to leach in artificial seawater under conditions that mimic those used in particle toxicity studies. Plastics included were polyethylene, polypropylene, polyvinyl chloride, high-density polyethylene and polystyrene. Leachable monomers and oligomers were found in three of the five plastics tested: polyvinyl chloride, high-density polyethylene and polystyrene. Leached compounds from polyvinyl chloride were not identified due to time limitations. Aliphatic hydrocarbons in the size C14-C22 were leached out from high-density polyethylene in the concentration range 0.47 × 10-3 – 1.13 × 10-3 μg ml-1 within 24 hours. Polystyrene was found to leach styrene monomer which reached a concentration of 0.17 μg ml-1 within 24 hours.

Microplastics take hundreds to thousands of years to degrade in nature, and pose a threat to the environment. A photocatalytical degradation method have been developed to take advantage of solar light to degrade microplastics, however it takes several months to degrade microplastics with the process. The purpose of this study is to enhance the degradation rate of microplastics by synthesizing a material where photocatalysis is combined with Fenton reaction. A material with zinc oxide nanorods coated with tin oxide and decorated with iron particles (𝑍𝑛𝑂/𝑆𝑛𝑂2/𝐹𝑒0) was synthesized and used to degrade methylene blue, polystyrene and polypropylene. The result show that the degradation rate with a 𝑍𝑛𝑂/𝑆𝑛𝑂2/𝐹𝑒0 – sample is faster than with a 𝑍𝑛𝑂 – sample, and that it can be used to degrade polystyrene and polypropylene.Students’ view on researchers can affect the development of their interest and attitude towards science. Study visits to laboratories have been used to increase students’ interest and give them new experiences. The purpose of this study is to investigate what and how high school students learn during a study visit to a nanotechnology laboratory, and how the study visit affects high school students’ interest and motivation for research and learning. A study visit with 5 stations was organized, and students were given a questionnaire about what they learned during the study visit. Thematic analysis was used to analyze the students’ answers. The result shows that the study visit increased students’ interest in research, and the importance of designing stations so that they are connected to students’ previous knowledge and are within their proximal development zone.<br>Mikroplaster tar hundratals till tusentals år att bryta ner i naturen och utgör ett hot mot miljön. En fotokatalytisk nedbrytningsprocess har utvecklats där solljus utnyttjas för att bryta ner mikroplaster, dock tar det flera månader att bryta ner mikroplaster med den processen. Syftet med denna studie är att förbättra nedbrytningshastigheten av mikroplaster genom att syntetisera ett material där fotokatalys kombineras med Fenton-reaktion. Ett material med zinkoxid nanorör belagda med tennoxid och dekorerade med järnpartiklar (𝑍𝑛𝑂/𝑆𝑛𝑂2/𝐹𝑒0) syntetiserades och användes för att bryta ner metylenblått, polystyren och polypropen. Resultatet visar att nedbrytningshastigheten med 𝑍𝑛𝑂/𝑆𝑛𝑂2/𝐹𝑒0 – materialet är snabbare än med ett 𝑍𝑛𝑂 – material, och att 𝑍𝑛𝑂/𝑆𝑛𝑂2/𝐹𝑒0 – materialet kan användas för att bryta ned polystyren och polypropen.Elevers syn på forskning och forskare kan påverka utvecklingen av deras intresse och inställning till vetenskap. Studiebesök på laboratorier har använts för att öka elevernas intresse och ge dem nya erfarenheter. Syftet med denna studie är att undersöka vad och hur gymnasieelever lär sig under ett studiebesök i ett nanotekniklaboratorium och hur studiebesöket påverkar gymnasieelevernas intresse och motivation för forskning och lärande. Ett studiebesök med 5 stationer organiserades och eleverna fick ett frågeformulär om vad de lärde sig under studiebesöket. Tematisk analys användes för att analysera elevernas svar. Resultatet visar att studiebesöket ökade elevernas intresse för forskning och vikten av att utforma stationer så att de är kopplade till elevernas tidigare kunskaper och ligger inom deras proximala utvecklingszon.

Plasty, pronikající do životního prostředí ať už neúmyslně či záměrně, mohou být fragmentovány za vzniku částic v řádu mikrometrů (tzv. mikroplastů) a znečišťovat tak půdní systémy. Doposud vyvinuté analýzy pro stanovení mikroplastů v půdách jsou především zaměřeny na kvalitativní stanovení, nicméně i jejich provedení se zatím stále potýká s různými úskalími. Navíc, téměř všechny tyto analýzy vyžadují časově náročnou předúpravu vzorku. V této studii jsme se zaměřili na vývoj nové analytické metody pro kvantitativní stanovení mikroplastů polyvinylchloridu (PVC) a polystyrenu (PS) v půdách bez předchozí úpravy vzorku pomocí termogravimetrické analýzy spojené s hmotnostní spektrometrií (TGA-MS). Pro analýzu byly použity vzorky modelové půdy s nízkým obsahem organického uhlíku, které byly spikovány na výslednou koncentraci 0,23–7 hm% PVC či PS. Vzorky byly pyrolyzovány s teplotním krokem 5 K min–1 až na teplotu 1000 °C. Pyrolýzní plynné produkty byly následně analyzovány s využitím hmotnostního spektrometru. Získaná data byla normalizována pomocí externího standardu (šťavelan vápenatý). Limity detekce se pohybovaly v rozmezí 0,08–5,3 hm% pro PVC a 0,005–0,7 hm% pro PS v závislosti na zvoleném m/z. Limity kvantifikace pak byly 0,3–17,7 hm% pro PVC a 0,002–2,2 hm% pro PS. Výsledky dokazují, že spojení TGA-MS může být konkurující semikvantitativní metodou pro stanovení mikro-PVC a mikro-PS v půdě s nízkým obsahem organického uhlíku.

Depuis 70 ans, les débris plastiques dont la fin de vie a été négligée par les sociétés humaines s’accumulent dans les océans. L’évaluation des effets engendrés par cette contamination ubiquitaire est une préoccupation majeure, notamment au regard des micro- et potentiels nanoplastiques (MNP ; &lt; 5 mm) du fait de leur biodisponibilité pour la plupart des organismes marins. L’objectif de cette thèse était de déterminer les effets des MNP sur les jeunes stades de vie d’une espèce ingénieure des habitats côtiers, l’huître creuse Crassostrea gigas. Les impacts des MNP sur ces jeunes stades sont apparus dépendants de la taille des particules. Le rapport surface/volume important des nanosphères de polystyrène (nano-PS ; 50 nm) a favorisé les interactions avec les gamètes et embryons, induisant une inhibition de la fécondation et de l’embryogénèse tandis que les microsphères (0,5 et 2 μm) n’ont causé aucun effet phénotypique visible. La toxicité des nano-PS est apparue dépendante de leurs propriétés de surface (e.g groupements chimiques, charge) qui dirigent leur agrégation dans l’eau de mer et les interactions avec les membranes biologiques. Les nano-PS cationiques, qui restent à l’échelle nanométrique dans l’eau de mer, sont à l’origine des effets toxiques les plus marqués. L’exposition embryonnaire à une dose non létale a notamment diminué les performances larvaires et modulé la réponse de la génération suivante à une réexposition embryonnaire. Toutefois, ces effets néfastes sont observés à des concentrations numéraires supposément non-représentatives de l’environnement actuel (la quantité de NP n’étant pas caractérisée en mer à ce jour), suggérant un risque limité des micro- et nanosphères de polystyrène sur les jeunes stades de C.gigas. Les prochaines études devront tenir compte de la complexité et de la réalité des MNP environnementaux (e.g. polymères, formes, contaminants adsorbés, concentrations) sur plusieurs générations de bivalves dans le but d’appréhender plus précisément le risque pour les écosystèmes côtiers<br>For 70 years, mismanaged plastic waste accumulates in the oceans. Risk assessment of this contamination is a major concern, especially regarding micro- and presumably nanoplastics (MNP; &lt;5 mm) which are bioavailable for most marine species. The objective of this thesis was to assess adverse effects of MNP to early life stages of the oyster Crassostrea gigas, a key engineer species in coastal ecosystems. MNP toxicity on oyster young stages depended on the particle size. The high surface area- to - volume ratio of polystyrene nanobeads (nano- PS; 50 nm) promoted their reactivity and interactions with biological membranes of gametes and embryos, leading to an inhibition of the fertilization and embryogenesis success while 0.5 and 2 μm polystyrene beads had any detectable effects. The nano-PS toxicity depended on the particle surface properties (e.g. surface functionalization and charge) which govern their aggregation in seawater and affinity with biological membranes. Furthermore, cationic nano- PS which remained at nanometric scale in seawater, had the highest toxic potential to oyster gametes and embryos. Embryonic exposure to these particles at a non-lethal dose reduced first generation larval performances and modulated larval growth at the second generation in response to the same embryonic exposure. All adverse effects were observed at supposedly unrealistic environmental concentrations (no in situ data exists on NP), suggesting low risk of polystyrene beads to oyster early life stages. Future studies will have to take into account the complexity and reality of MNP in oceans (e.g. polymer and shape diversity, concentrations, contaminants adsorption) to assess effects on bivalve species across generations in order to establish more accurately the risks for coastal environments

Dissertação de mestrado, Biologia Marinha, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2016<br>Nowadays there is an increasing resilience of plastics as an everyday item. With the rapid increase in their production and spread, plastic debris are accumulating in the marine environment where they are fragmented into smaller pieces. One of the most produced polymer, and accordingly, more common in the marine environment is the polystyrene (PS). Ranges of organisms, especially invertebrates, are vulnerable to the exposure of microparticles. However, the impacts of microplastics (< 5mm) in the marine systems are poorly understood. The aim of this study was to assess the ecotoxicity of PS microplastics in different tissues of the peppery furrow shell Scrobicularia plana and select the most appropriate biomarkers to evaluate microplastics effects. Clams were exposed to 1 mg L-1 of PS microplastics (20 μm) for 14 days, followed by a 7 days depuration. Microplastics accumulation in gills and digestive gland was analysed through Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFT) and their effects by a battery of biomarkers of oxidative stress (superoxide dismutase, catalase, glutathione peroxidases and glutathione-S-transferases), genotoxicity (comet assay to evaluate DNA damage), neurotoxicity (acetylcholinesterase activity) and oxidative damage (lipid peroxidation). Results indicate that microplastics were accumulated in both organs, but more significant in the gills and were not completely eliminated after 7 days of depurarion. Microplastics accumulation induced an oxidative stress response in both tissues. The overall results on oxidative stress biomarkers indicated that short-term exposure to PS microplastics induce major perturbations, as revealed by the effects on the total antioxidant capacity, DNA damage, neurotoxicity and thus oxidative damage. The results highlighted the potential source of PS toxicity for human health and the marine environment and that S.plana is a significant target of PS microplastics ecotoxicity and can be a suitable biomonitor for assess their environmental risk.<br>Hoje em dia há uma resiliência crescente dos plásticos como um item do dia-a-dia para fins comerciais, industriais e terapêuticos. No entanto, a sua produção, o rápido crescimento e distribuição tem dado origem a sérias implicações ambientais. O consumo de plásticos em muitos países europeus indica que as resinas plásticas mais utilizadas desde 2007 são polietileno de baixa densidade (PEBD) e polietileno de alta densidade (HDPE), polipropileno (PP), cloreto de polivinilo (PVC), polietileno tereftalato (PET) e poliestireno (PS). O poliestireno (PS) é um dos plásticos mais utilizados em todo o mundo e tem sido detetado nos oceanos sob a forma de micro e nano partículas. Tem-se verificado que o PS tem um impacto ambiental considerável, nomeadamente em espécies marinhas. Recentemente, foram identificadas no ambiente marinho partículas microscópicas omnipresentes - os microplásticos - definidos como partículas com menos de 5 mm de diâmetro, de acordo com a National Oceanic and Atmospheric Administration dos Estados Unidos da América. São considerados um poluente marinho emergente e, até à data, têm sido detetados em muitos habitats e numa variedade de espécies marinhas e de água doce. Assim, é importante entender a sua distribuição no ambiente marinho e as implicações sobre os habitats, biodiversidade e bem-estar das espécies marinhas. Os efeitos biológicos dos microplásticos nos organismos dependem do seu tamanho sendo que, quanto menor, maior será a acumulação e o efeito a nível celular. Apesar da preocupação relacionada com a ingestão, os efeitos dos microplásticos em populações marinhas e as suas implicações para a cadeia alimentar ainda não são bem conhecidos. Os invertebrados marinhos são particularmente suscetíveis aos microplásticos, por causa do tamanho e modo de alimentação. Uma vez que o modo de ação e o risco biológico dos microplásticos ainda não são muito claros, esta dissertação avaliou a acumulação e os efeitos dos microplásticos de poliestireno (20 μm) na lambujinha Scrobicularia plana, de forma a avaliar o potencial risco ecotoxicológico para os diferentes níveis de organização biológica e selecionar o biomarcador mais apropriado para determinar os efeitos dos microplásticos. Relativamente à parte experimental, após a recolha, os animais tiveram um periodo de aclimatação de 7 dias. Seguidamente foram expostos a uma concentração de PS microplásticos (1 mg L-1) durante 14 dias, juntamente com um grupo de controlo, ao qual se seguiu um período de depuração de 7 dias. Os animais foram recolhidos em diferentes dias de exposição, nomeadamente nos dias 0, 3, 7, 14 e 21. Inicialmente, as características dos microplásticos e o seu comportamento na água do mar foram analisados em termos de forma, tamanho, carga superficial (potencial zeta), agregação, turbidez e taxa de sedimentação. Seguidamente, avaliou-se a acumulação dos microplásticos nas brânquias e na glândula digestiva através da observação ao microscópio ótico das partículas presentes na hemolinfa, e pela técnica de espectroscopia por refletância difusa no infravermelho com transformação de Fourier (DRIFT). Para o estudo da toxicidade dos microplásticos de PS uma bateria de biomarcadores foi analisada nas brâquias e na glândula digestiva incluindo: stress oxidativo (superóxido dismutase - SOD, catalase - CAT, glutationa peroxidases - GPx e glutationa-S-transferases - GST), genotoxicidade (danos no ADN), neurotoxicidade (actividade da enzima acetilcolinesterase), e dano oxidativo (peroxidação lipídica). Os microplásticos usados neste estudo foram micropartículas esferóides com um tamanho de 20 ± 0.02 μm e densidade de 1.05 g cm-3. Em água do mar, os microplásticos de PS tendem a formar pequenos agregados com uma carga superficial negativa (potencial zeta = -12.4 ± 2.36 mV). A taxa de sedimentação rápida e lenta dos microplásticos na água do mar foi de 1.04 x 10-1 e 1.16 x 10-3 h-1, respetivamente, confirmando a sua tendência para sedimentar nos tanques de exposição, após as primeiras duas horas. No que diz respeito à acumulação dos microplásticos de PS nos tecidos, as brânquias apresentaram um padrão de acumulação crescente ao longo do tempo de exposição, com uma possível recuperação no final do período de depuração, através da eliminação dos microplásticos de PS quase na sua totalidade. Em relação à glândula digestiva, a acumulação de microplásticos de PS é evidente, no entanto, não apresentou o mesmo padrão de aumento observado nas brânquias. Os resultados indicaram que a acumulação foi mais eficiente nas brânquias do que na glândula digestiva. A toxicidade dos microplásticos de PS nas lambujinhas é dependente do tecido e do tempo de exposição e envolve mudanças na atividade das enzimas antioxidantes, stress oxidativo, neurotoxicidade e danos no ADN. As brânquias são o orgão que responde mais ativamente ao stress oxidativo induzido pelos microplásticos de PS, com efeitos associados ao aumento da atividade das enzimas antioxidantes (SOD, CAT, GPx) e de biotransformação (GST). Na glândula digestiva verificou-se um aumento da atividade da SOD, CAT e GPx. Comparando as atividades das enzimas antioxidantes e de biotransformação dos dois órgãos (brânquias e glândula digestiva), a atividade da CAT foi a única que aumentou na glândula digestiva em relação às brânquias. Após o período de depuração verificou-se um aumento da atividade da SOD e GPx nas brânquias. Na glandula digestiva ocorreu um aumento da atividade da CAT e uma diminuição da atividade da GST. Verificou-se ainda um efeito genotóxico e neurotóxico causado pelos microplásticos de PS. O efeito genotóxico traduziu-se pelo aumento da percentagem de ADN presente na cauda do cometa (DNA Tail) e no comprimento da cauda do cometa e pela proporção de ADN presente na cauda (Olive Tail Moment). Também no período de depuração se verificou um aumento para estes dois parâmetros. O efeito neurotóxico dos microplasticos de PS é suportado pela diminuição da atividade da acetilcolinesterase após o primeiro dia de exposição. De uma forma geral, o dano oxidativo foi maior na glândula digestiva do que nas brânquias. Nas brânquias o dano foi menor após o ínicio da exposição aos microplásticos. Na glândula digestiva verificou-se um aumento progressivo até ao 7º dia. Após o período de depuração, apenas se verificaram diferenças significativas na glândula digestiva, com uma diminuição do nível de LPO em relação ao ultimo dia de exposição (dia 14). Analisando os resultados no seu conjunto, as brânquias aparentam ser um órgão essencial na proteção de S. plana contra o efeito dos microplásticos de PS, uma vez que a resposta das enzimas antioxidantes e de biotransformação foi mais notória neste orgão do que na glândula digestiva, traduzindo-se numa maior toxicidade. Estes resultados indicam que, possivelmente, S. plana lida com a produção de espécies reativas de oxigénio (ROS) através da indução das defesas antioxidantes, o que, por conseguinte, limita o ataque de ROS nas membranas celulares, impedindo que haja peroxidação lipídica nas brânquias. O período de depuração não parece ser suficiente para a eliminação dos microplásticos de PS. Durante o período de depuração, as brânquias de S. plana aparentam possuir baixa capacidade de eliminação de PS, sendo o principal órgão de contacto com os microplásticos, enquanto que a glândula digestiva parece eliminar mais facilmente as micropartículas.

Expanded polystyrene (EPS) is among the most demanded plastic commodities due to its attractive properties of lightness and durability. Such desirable characteristics present, however, an environmental threat, as it is easily transported until it reaches the ocean, where it is likely to be fragmented into microplastics. Despite the efforts for EPS waste management, sustainable and efficient solutions are needed. Biotechnology-based solutions have been investigated for their potential. Herein, Zalerion maritimum and Nia vibrissa were screened for their potential in the biodegradation of EPS, based on the quantified mass differences in both the fungus and the microplastic pellets. In a preliminary evaluation, the highest removal percentage obtained by Z. maritimum, in 28 days, was 66% and the lowest was 25%. In a second assay, the removal percentages were lower. An optimization assay, using Central composite design (CCD), was conducted to obtain optimum values for EPS concentration, pellet dimension and malt extract concentration. These were, respectively, 0.1458 g/L, 1-1.40mm and 20 g/L. Although Z. maritimum showed ability to degrade EPS, the process appeared to be variable and required high amounts of malt extract. Therefore, N. vibrissa was screened for its potential also. In a preliminary assay, N. vibrissa achieved higher microplastic removal percentages. Consequently, a biodegradation assay in optimized medium was conducted. However, the best removal percentage obtained was of 47±16%.<br>A baixa densidade e durabilidade do poliestireno expandido (EPS) colocam-no entre os plásticos mais versáteis e com maior quota de mercado. Estas mesmas propriedades levantam preocupações ambientais, uma vez que o tornam facilmente transportável até aos oceanos, onde é suscetível à fragmentação, originando microplásticos. Apesar de existirem soluções convencionais para a reciclagem deste plástico, apresentam limitações, sendo necessária a procura de métodos alternativos eficientes e mais sustentáveis. Soluções biotecnológicas têm sido investigadas. No presente trabalho, o potencial de biodegradação do EPS pelos fungos marítimos Zalerion maritimum e Nia vibrissa foi avaliado através da quantificação de variações de massa apresentadas pelas amostras de partículas de plástico e biomassa de fungo usadas, durante ensaios de exposição ao plástico. Na avaliação preliminar, em 28 dias, a melhor % de remoção atingida pelo fungo Z. maritimum foi de 66.2%, sendo a mais baixa de 25.0%. Num segundo ensaio, as percentagens de remoção apresentaram-se inferiores. Assim, num seguinte ensaio de otimização, utilizando o modelo Central composto (CCD), pretendeu-se maximizar a resposta e avaliar a influência das variáveis – concentração de EPS, tamanho das partículas e concentração de extrato de malte, na resposta -percentagem de remoção de microplásticos. Obtiveram-se, respetivamente, os seguintes valores ótimos - 0.1458 g/L, 1-1.40mm e 20 g/L. Apesar de apresentar potencial para a biodegradação do EPS, o processo com o fungo Z. maritimum mostrou-se variável e exigindo elevadas quantidades de malte. Consequentemente, o fungo N. vibrissa foi também avaliado, sendo que, num primeiro ensaio, atingiu percentagens superiores de remoção de microplásticos. Um novo ensaio foi realizado com este fungo em meio otimizado, tendo-se obtido como melhor percentagem de remoção 47±16%.<br>CESAM (UID/AMB/50017); IF/00407/2013/CP1162/CT0023; POCI-01-0145-FEDER-028740; SFRH/BPD/122538/2016<br>Mestrado em Biotecnologia

碩士<br>國立臺灣大學<br>海洋研究所<br>106<br>Being able to quantify microplastics in the gut of zooplankton is a critical environmental concern. The amount of extracted microplastics may be less than the real amount in the gut of zooplankton, due to loss during the extraction and quantification procedures. These losses could vary depending on the size and concentration of microplastics. To tackle this difficulty, I tried various protocols to extract and quantify microplastics in copepods through feeding experiments. In this study, adult Pseudodiaptomus annandale were fed with polystyrene beads of 9-25 μm, using a series of concentration from 1- 10000 beads/ mL. To optimize extraction protocol, I tried proteinase-K and sodium hypochlorite to digest biological materials. I found that proteinase-K enzyme extraction method is the most efficient, with no noticeable impact on microplastics. Extracts from digestion were then filtered on a glass filter. The results of feeding experiments indicate that ingestion of 25-μm beads was low, suggesting that this size was out of feeding range and thus no further analysis was carried out. Using a series of beads concentration for the 20-μm beads, I found that the ingestion amount and extraction amount are correlated. My optimized enzyme extracting protocol had an extraction rate at an average of 90.6% for 20-μm beads. I established the extraction calibration curve (linear regression, r2=0.9997, slope= 0.9454), which allows to back-calculate the ingestion amount from the bead counts in the extract. Due to difficulty in counting 9-μm beads, ingestion amount was estimated by the intensity of luminescent light within the gut area while extraction amount was estimated through a transect subsampling procedure. Ingestion in the gut and transect sampling on the filter were analyzed to establish the extraction calibration curve. I found that the ingestion amount and extraction amount are correlated for 9-μm beads, which allows establishing the extraction calibration curve (linear regression, r2=0.772). To investigate the samples in natural systems, I analyzed the filter-feeding copepods that are abundant in the southern East China Sea. Paracalanidae and Calanidae copepodids (body length > 300 μm) were chosen for examination. The optimized enzyme extracting protocol was applied before testing identification and quantification methods on the extracts of copepods. I tried visual characterization, spectrometry instruments, flow cytometer and microscope (FlowCAM®), fluorescent Nile red dye, and fluorescent microscope; these methods are commonly used in larger organisms. Methods capable of analyzing particles below 50 μm include fluorescent microscope and micro-RAMAN. Despite using the optimal enzyme extracting protocol and quantification methods, I did not find any microplastic from the extract. This result may be because my protocol has low extraction efficiency for microplastics or the concentration of microplastics inside the gut of those copepod specimens are too low to be detectable.

碩士<br>國立臺灣大學<br>生態學與演化生物學研究所<br>107<br>Microplastics are plastic debris smaller than 5 mm in diameter. It has been shown that microplastics would cause many adverse impacts on zooplanktons such as reduce feeding rate, delay development and decrease fecundity. However, most studies evaluate the effect of microplastics focus on holoplankton, but relatively less studies focus on meroplankton. In the present study, we used the barnacle Amphibalanus amphitrite as a model organism for meroplankton to investigate the effects of four different sizes of polystyrene microplastics (diameter 1.7, 6.8, 10.4, 19.0 µm respectively) at four concentrations (1, 10, 100, 1000 beads mL-1). We found that stage II nauplii of A. amphitrite were able to ingest all four sizes of microplastics and efficiently egested them within several hours. Larval mortality, development time, growth rate, settling rate and metamorphosis percentage of microplastic treatments were not significantly different from that of control after being exposed to four different sizes of microplastics at any concentration from nauplii to cyprids. Moreover, feeding rate of nauplii (stage II- stage VI) were barely impaired at the concentration of 1000 beads mL-1. Overall, our results suggest that polystyrene microplastics have very limited impacts on the entire larval cycle of barnacle A. amphitrite. The microplastic exposed larvae could still successfully metamorphose to juvenile stage. We further extended the microplastic exposure over barnacle generations, continuously fed barnacle adults with same size of microplastic until they reproduced next generation offspring. Our results found that microplastics did not significantly affect adults of first generation but significantly increase larval mortality of next generation offspring, suggesting that microplastics have transgenerational effects. We also compared the larval mortality and retention time of microplastics between barnacle larvae from different habitats and climatic zones (Fistulobalanus albicostatus, Tetraclita japonica formosana, Chelonibia testudinaria, Neoacasta sp., Euacasta dofleini, Darwiniella angularis, Chthamalus dalli, Balanus glandula). We found that all barnacle species did not suffer increase mortality upon exposure to microplastics, but the retention time of microplastics significantly differed between barnacles lived in different habitats. Rocky shore and coral reef associated species have about 3-4 times longer microplastic retention time than the muddy shore species, suggesting that rocky shore and coral reef associated species might be more vulnerable to microplastic pollution.

碩士<br>國立臺灣大學<br>生物環境系統工程學研究所<br>107<br>Microplastics (MPs), are defined as tiny plastics with particle size less than 5 mm. Ecological concerns and health risks of MPs contamination have been attracting a worldwide attention within a decade. While a large body of literature has shown that MPs are highly likely to be accumulated in aquatic and terrestrial biota, information about the toxic interactions of MPs on organisms from a mechanistic point of view is more limited. This thesis filled this knowledge gap by assessing polystyrene (PS)-MPs in zebrafish, red tilapia, and mice systems based on a toxicokinetic/toxicodynamic (TK/TD) modeling to quantify organ-bioaccumulation and biomarker responses appraised with published datasets. Exposure risks for aquatic model organisms including bivalves were also presented by utilizing the published environmentally relevant concentration data of PS-MPs in marine and freshwater ecosystems. The organ-specific TK-parameters and mean residence times for zebrafish, red tilapia, and mice posed by size-specific PS-MPs could be obtained. The highest uptake rates were in the liver of zebrafish, in the gut of red tilapia and mice, respectively. Results showed that steady-state bioconcentration factors (BCFsss) of PS-MPs among all organs were much greater than 1, indicating the bioaccumulating potential of PS-MPs in animals. In comparison to mice, zebrafish have commonly much greater BCFsss in organs. The sensitivities of biomarkers regarding immunological response, oxidative stress, detoxification, and energy and lipid metabolisms to PS-MPs in liver of organisms were determined by the TD assessment. These concentration-effect relationships based on the Hill model varied with species used, exposure time, and particle size of PS-MPs in each system. As the result, toxicity thresholds of PS-MPs were in a large variability. Results demonstrated that the most sensitive biomarkers in bivalves, zebrafish, red tilapia, and mice systems, based on strict threshold concentrations, were phagocytic cells, superoxide dismutase (SOD), 7-ethoxyresorufin O-deethylase, and SOD, respectively. A risk-based probabilistic model was further used to characterize the potential hazards of marine bivalves and freshwater fish in response to predicted environmental concentrations of PS-MPs quantified by exceedance risks and risk quotients. Among five global plastic-filled gyres, the highest and lowest risks were occurred in the North Pacific and South Pacific Oceans for bivalves, respectively. For freshwater fish, the Winyah Bay in USA appeared to be the greatest risks among the selected local areas. The present results warranted further attention on worldwide MPs pollution posing hazards to aquatic organisms, particularly sensitive species like zebrafish taking the brunt of the long-term toxicity risk. Moreover, the mice-based TK parameters and threshold criteria greatly assist in designing robust researches to evaluate MPs consumption by humans. An extrapolation framework was proposed for mechanistically estimating toxicity thresholds of MPs from mice to humans in a health risk assessment perspective. Overall, results derived from the TK/TD assessment, the Weibull threshold model, and the ecotoxicological risk assessment could be adopted to rapidly evaluate MPs-induced toxicities at various concentrations. The strict thresholds could be recommended as criteria for environmental management of MPs and offer a tool-kit in establishing the scheme for risk assessment of human consumption.