1,721,145 research outputs found
Wastewater treatment plants as a pathway for microplastics: Development of a new approach to sample wastewater-based microplastics
No full textWastewater effluent is expected to be a pathway for microplastics to enter the aquatic environment, with microbeads from cosmetic products and polymer fibres from clothes likely to enter wastewater treatment plants (WWTP). To date, few studies have quantified microplastics in wastewater. Moreover, the lack of a standardized and applicable method to identify microplastics in complex samples, such as wastewater, has limited the accurate assessment of microplastics and may lead to an incorrect estimation. This study aimed to develop a validated method to sample and process microplastics from wastewater effluent and to apply the developed method to quantify and characterise wastewater-based microplastics in effluent from three WWTPs that use primary, secondary and tertiary treatment processes. We applied a high-volume sampling device that fractionated microplastics in situ and an efficient sample processing procedure to improve the sampling of microplastics in wastewater and to minimize the false detection of non-plastic particles. The sampling device captured between 92% and 99% of polystyrene microplastics using 25 μm–500 μm mesh screens in laboratory tests. Microplastic type, size and suspected origin in all studied WWTPs, along with the removal efficiency during the secondary and tertiary treatment stages, was investigated. Suspected microplastics were characterised using Fourier Transform Infrared spectroscopy, with between 22 and 90% of the suspected microplastics found to be non-plastic particles. An average of 0.28, 0.48 and 1.54 microplastics per litre of final effluent was found in tertiary, secondary and primary treated effluent, respectively. This study suggests that although low concentrations of microplastics are detected in wastewater effluent, WWTPs still have the potential to act as a pathway to release microplastics given the large volumes of effluent discharged to the aquatic environment. This study focused on a single sampling campaign, with long-term monitoring recommended to further characterise microplastics in wastewater.Griffith Sciences, Griffith School of EnvironmentNo Full Tex
Occurrence of Microplastics in Five Fresh Seafood Species Sourced from the Gold Coast, Australia
No full textDue to the current rate of plastic manufacturing and inadequate management of plastic waste, plastics have emerged as a significant challenge and environmental threat worldwide. Microplastics (MPs), defined as plastic particles smaller than 5 mm, have gained global attention due to their widespread distribution, bioavailability, and potential health implications for humans. The marine environment, being the ultimate destination for various contaminants, including MPs, poses a particular concern as seafood contaminated with MPs can cause health risks since seafood plays a significant role as a major protein source globally. The Gold Coast is popular as a vacation and surfing destination in Australia and is characterised by high population density. Therefore, this research study focused on determining the occurrence of MPs in five selected seafood species popular in local fish markets in the Gold Coast, Australia.
This thesis comprises four chapters. Chapter 1 provides the study's background and underscores its significance. Chapter 2 presents a comprehensive literature review analysing previous research on MPs, highlighting their toxic effects on human health, aquatic fauna, and the broader aquatic ecosystem. Furthermore, Chapter 2 discusses recent studies relevant to the present investigation and methodological advancements in MP research, including laboratory analysis techniques and quality assurance/quality control (QA/QC) measures. Chapter 3 constitutes the primary component of the thesis, the research study titled "Occurrence of Microplastics in Five Fresh Seafood Species Sourced from the Gold Coast, Australia", while Chapter 4 offers a general discussion and conclusion. [...]Thesis (Masters)Master of ScienceSchool of Environment and ScGriffith SciencesFull Tex
The use of non-targeted proteomics and in vitro bioassays as a non-destructive approach towards the development of biomarkers of contaminant exposure in threatened marine wildlife
No full textBiomarkers of chemical exposure and effect are an important tool for monitoring the
health of threatened species that are vulnerable to the adverse effects of prolonged
contaminant exposure. However, there are many challenges that have limited the
discovery of new biomarkers of chemical exposure in protected species, particularly the
constraint on the use of destructive methods such as in vivo experimentation. This thesis
first examines the current methods of biomarker discovery as reported in the literature
to identify what methods future research in this field should focus on. A systematic
quantitative review of methods of non-destructive biomarker discovery in wildlife
highlighted the hinderance of these limitations on current research as well as the paucity
of studies harnessing in vitro techniques (Chapter 2). The use of in vitro bioassays is not
uncommon in ecotoxicology, however, these assays are largely targeted at one or
several known markers. Non-targeted proteomics analyses allow for the discovery of
new biomarkers, which is important considering wildlife may continually be exposed to
new compounds and mixtures. Therefore the application of in vitro and in vivo nontargeted
proteomic analysis as a tool for biomarker discovery was examined. To do so,
sea turtles were used as a model species due to their priority conservation status and
their susceptibility to the adverse effects of contaminant exposure. Cell lines derived
from sea turtles exposed in vitro to environmentally relevant contaminants were used as
a model for the in vitro analyses. Firstly, experimental sources of variation on protein
expression (time, concentration and contaminant type) were explored (Chapter 3)
revealing a strong effect of exposure time on observed proteomic changes and little
effect from concentration. Furthermore, potential candidate biomarkers were discovered
and the relevance of this method to in vivo molecular responses was demonstrated with
the observation of known in vivo markers of exposure dysregulated in response to
chemical exposure. Then, the influence of biological sources of variation (tissue type) were examined with cells derived from several tissue types exposed in vitro to
contaminants (Chapter 4). Different tissue types showed a different response to
contaminant exposure and known in vivo biomarkers of exposure were again observed.
Furthermore, potential new biomarker candidates were identified that would be
beneficial for future research in this field to explore. Finally, non-targeted proteome
profiling was applied to biological samples of wild-caught animals to examine its
potential in biomarker discovery (Chapter 5). The proteome of the blood plasma of three
Southeast Queensland sea turtle populations exposed to different chemical profiles were
compared, and distinct differences in population protein expression were observed.
These differences indicated altered immune states between populations, which could be
caused by contaminant and/or pathogen exposure. In conclusion, this novel method of
non-targeted proteomic analysis of both in vitro and in vivo samples provides a wealth
of information about how contaminants affect sea turtles at the cellular and whole
organism level and is a promising avenue to enhance wildlife toxicology. However, it
was discovered that it is challenging to draw correlations between in vivo and in vitro
global protein expression, and furthermore that sources of experimental variation can
greatly influence the outcomes. Therefore, it is vital that future studies on this area focus
on reproducibility of these sensitive methods before fully utilising them for directing
wildlife toxicology research.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Environment and ScScience, Environment, Engineering and TechnologyFull Tex
Microplastics in indoor and outdoor air: occurrence, human exposure assessment and mitigation
No full textPlastic pollution has become one of the most crucial environmental problems in the 21st century. MPs (plastic particles smaller than 5 mm) have attracted enormous attention due to their smaller size and omnipresence in almost all biotic and abiotic environmental compartments. Research to date has focused on MP pollution in aquatic and terrestrial environments, and our understanding of MP pollution in the atmospheric compartment is still in its infancy despite atmospheric transport being a significant dispersal pathway of global MP pollution. Out of the limited studies on AMPs, most have been conducted in high-income countries with established waste management practices. In contrast, only a few studies have looked at low-to-middle-income countries (LMICs), which are believed to be significant contributors to global plastic pollution. Many of these limited studies have also been derived from sampling atmospheric depositions using passive sampling techniques. However, active sampling of suspended AMP particles is arguably a more relevant method for evaluating human MP exposure via inhalation. Moreover, recent studies have identified AMPs deposited in all regions of the human lungs. Still, studies accurately quantifying the human exposure levels to AMPs and investigating appropriate methods to mitigate these exposures were limited. Hence, the overall aim of this thesis was to 1) summarise the current state of knowledge of AMP studies and highlight the knowledge gaps, 2) identify and quantify AMPs in indoor and outdoor locations of a high-income and a low-to-middle-income country using an active sampler and estimate possible human exposure levels to AMPs, and 3) investigate the suitability of terrestrial plants as a cost-effective candidate to retain and mitigate AMP exposure and the
influence of their leaf morphology in this retention. [...]Thesis (PhD Doctorate)Doctor of PhilosophySchool of Environment and ScGriffith SciencesFull Tex
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Identification and quantification of microplastics in wastewater treatment plant effluent: Investigation of the fate and biological effects
No full textMicroplastics (i.e., plastics particles < 5mm) are widespread emerging contaminants
that have been detected in various aquatic environments worldwide including
freshwater and marine ecosystems. Contamination of the environment with
microplastics has become an environmental issue due to the potential of plastics to
remain for thousands of years and to accumulate in the aquatic environment. The
abundance of microplastics in the aquatic environment is assumed to increase due to
continuous fragmentation of macro and microplastic debris, which can lead to a
decrease in the average size ranges of microplastics over time (Cole et al., 2011).
Moreover, concerns have been raised regarding the potential of microplastics to
physically (e.g., blockage of digestive tract) and chemically (e.g., leaching of sorbed
chemicals and toxic additives) harm aquatic organisms.
Microplastics can enter the aquatic environment from both aquatic-based and landbased
sources. Recently, wastewater treatment plants (WWTP) have been identified
as one of the important land-based sources of microplastics. While microplastics
have been reported in WWTP effluent in Asia, Europe, USA and Russia, little is
known about the presence of microplastics in Australian WWTP effluent. More
importantly, the lack of standardized techniques to sample and characterize
microplastics in environmental samples, especially in complex samples such as
wastewater, has led to inaccurate estimations of microplastic concentrations. In
response to the current knowledge gaps, a novel validated high-volume sampling
device was developed for in situ fractionation of microplastics from wastewater
effluent as part of this project. The developed method was applied to three Australian
WWTPs utilizing primary, secondary and tertiary treatments to provide a snapshot of
the fate and removal of microplastics during various wastewater treatment processes.
To achieve an accurate estimation of microplastics, the sampling technique was
combined with an efficient sample processing method. Microplastic polymer type,
shape and potential origin were further determined using microscopy analysis and
Fourier Transform Infrared (FTIR) spectroscopy. The efficiency of the sampling
device was found to be between 92 to 99% for 500 and 25 μm mesh screens. The
results showed that the concentrations of microplastics were 1.5, 0.6 and 0.2
microplastics per liter of effluent in primary, secondary and tertiary effluent,
respectively. It was also found that the majority of detected microplastics in the
studied WWTPs were polyethylene terephthalate (PET) fibers, which is assumed to
originate from synthetic clothing. Polyethylene (PE) beads and fragments, which may be associated with cosmetic products, were the second most frequently detected
type of microplastic. Despite a thorough sample processing method, FTIR
spectroscopy revealed that between 22 to 90% of the suspected microplastic particles
were in fact non-plastic particles. This study suggests that WWTPs can act as a
significant source of microplastics to the aquatic environment given the large volume
of wastewater discharged to the aquatic environment.
To date, the effects of microplastics on aquatic organisms have mostly been
examined using high and often unrealistic concentrations of microplastics (e.g.,
milligram per liter range). Moreover, while the presence of different types of
microplastics together in aquatic ecosystems has been widely reported, the potential
effects of microplastics when they occur as mixtures are largely unknown. To cover
these knowledge gaps, the potential adverse effects of wastewater-based
microplastics (such as fibers and beads) at lower concentrations on the freshwater
organism Ceriodaphnia dubia were evaluated. The acute (48 h) and chronic (192 h)
effects of PET fibers and PE bead microplastics on C. dubia were assessed alone and
as a binary mixture. The results showed a dose-dependent trend on survival, with C.
dubia more sensitive to PET fibers than PE microplastics. The 48 h EC50 value of
fibers was 1.5 mg/L compared to 2.2 mg/L for PE beads. The binary mixture of
microplastic beads and fibers demonstrated less than additive effects. EC50 values for
the chronic bioassay were 429 μg/L for fibers and 958 μg/L for PE microplastics. A
positive trend of decreasing growth (body size of adults) and reproduction rate
(number of neonates) with increasing microplastic concentration was observed for
both PE and fiber microplastics during the chronic bioassays. Using scanning
electron microscopy (SEM) we observed deformities, such as carapace and antenna
deformation, in C. dubia exposed to fibers at a high concentration, but not at the
lower (environmentally relevant) concentrations.
Given the likelihood that microplastics will eventually sink to the bottom sediment in
the aquatic ecosystem the effects of microplastics were investigated on a freshwater
sediment-dwelling organism (Chironomus tepperi) at environmentally relevant
concentrations of PE microplastics (500 particles/kgsediment). Possible size-dependent
effects of microplastics were also examined using four different size ranges of PE
beads including 1-4, 10-27, 43-54 and 100-126 μm. The results revealed that
exposure to an environmentally relevant concentration of microplastics had a
detrimental impact on the survival, growth (i.e., body length and head capsule) and
emergence of C. tepperi. The observed effects were strongly dependent on microplastic size with C. tepperi more sensitive to microplastics in the size range of
10-27 μm. No negative effects were observed on growth and survival of C. tepperi
exposed to the larger microplastics (100-126 μm), though a significant decrease in
the number of emerging adults was observed in the organisms exposed to the same
size range of microplastics. Further, SEM showed a significant reduction in the size
of the head capsule and antenna in C. tepperi exposed to microplastics in the size
range of 10-27 μm. These results showed that environmentally relevant
concentrations of microplastics in sediment can result in adverse effects on the
development and emergence of C. tepperi, with effects strongly dependent on
particle size.
Finally, we evaluated the effects of PE microplastics on the acute toxicity of a
pyrethroid insecticide (bifenthrin) to midge larvae (C. tepperi) in water. To test the
single and combined effects of bifenthrin and PE microplastics, C. tepperi larvae
were exposed to six concentrations of bifenthrin ranging from 0.1 to 3.2 μg/L in the
presence and absence of microplastics. To examine the possible effects of bifenthrin
and microplastics in synthetic and real water, the bioassays were performed in both
moderately hard water (MHW) and river water. We performed an uptake study using
three different size ranges of microplastics (10-27, 43-54, 100-126 μm) during 8-day
microplastics-spiked water exposure. The results showed that microplastics in the
size range of 10-27 μm were mostly ingested by C. tepperi larvae. Using this finding,
10-27 μm microplastics were selected for the bioassays. The results of the bioassays
using MHW demonstrated a significant decrease in the toxicity of bifenthrin in the
presence of microplastics. This is likely attributable to the tendency of bifenthrin to
bind to the microplastics, which reduces the bioavailability of bifenthrin to midge
larvae. However, in the bioassays conducted in river water with a total organic
carbon (TOC) concentration of 9.6 mg/L, no significant difference was observed
between the toxicity of bifenthrin to C. tepperi in the presence and absence of
microplastics. This is likely due to the interaction between organic carbon and
bifenthrin, which reduces the bioavailability of bifenthrin to C. tepperi larvae.
This thesis highlights that microplastic fibers and beads are released to the aquatic
environment from WWTPs, and that this can negatively affect survival, reproduction
and the life cycle of aquatic organisms (both pelagic and benthic) through
entanglement (fibers) and ingestion (beads). The effect of microplastics on chemical
contaminants is complex, and microplastics may act both as carriers but also as
“chelators” of chemicals in the water, thereby reducing their bioavailability.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Environment and ScScience, Environment, Engineering and TechnologyFull Tex
Investigation of Endocrine Disruption in Australian Aquatic Environments
No full textThere are over 40,000 chemical compounds registered for use in Australia; however, very few of these have been monitored in aquatic receiving environments. Furthermore, their toxicological effects on fish species in Australia are largely unknown. Studies on trace organic contaminants (TrOCs) and endocrine active compounds (EACs) in Australia have focused on wastewater effluents, and limited knowledge exists regarding the relative contribution of different potential sources of TrOCs and EACs to the aquatic environment (e.g. pesticide run off, animal farming operations, urban stormwater, industrial inputs). This study combined chemical, in vitro, in vivo and in situ techniques to determine the extent of endocrine disruption in fish living in 73 rivers across mainland Australia. These rivers were sampled quarterly for one year to determine the chemical concentrations of 56 compounds including 42 TrOCs and 14 EACs. Monitored chemicals include: 30 pharmaceuticals, 4 personal care products, 3 industrial compounds, 7 pesticides, 10 natural hormones and 2 synthetic hormones. At least one of the 56 compounds was detected in 99% (281 of 285) of grab river water samples. On average five compounds were detected per sample, with a median of four and a maximum of 21 compounds per sample. [...]Thesis (PhD Doctorate)Doctor of Philosophy (PhD)Griffith School of EnvironmentScience, Environment, Engineering and TechnologyFull Tex
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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