139 research outputs found
On the harmonization of methods for measuring the occurrence, fate and effects of microplastics
No full textWelcome to this Analytical Methods themed issue on microplastics in the environment, guest edited by Chelsea M. Rochman, Fiona Regan and Richard C. Thompson. The editors hope that this editorial will facilitate discussions that lead toward harmonized methods that are informed by hypotheses, and ultimately produce data that can be synthesized and used to inform effective local and global policies that prevent and mitigate microplastics.</p
Transport, Fate, and Effects of Microplastics in a Rapidly Changing Arctic
No full textMicroplastics (<5 mm) have been deemed a contaminant of emerging Arctic concern. Microplastics are multi-dimensional in that they range in morphology, size, and chemical cocktail (e.g., additives, sorbed contaminants) and are hypothesized to serve as an important transport mechanism for chemical contaminants to and within northern ecosystems. While microplastics and plastic additives have been identified across Arctic ecosystems, there is a need to better understand the transport, fate, and effects of microplastics and their additive chemicals. Here, I explore these three themes through a series of field observations and laboratory experiments. First, in Chapter 2 of this dissertation, I show that while seabirds may be an important transport pathway of microplastics to the Arctic, there are other regional sources that need to be considered. In Chapters 3 and 4, I explored the role of long-range atmospheric transport of microplastics via atmospheric deposition. In Chapter 3, using a high-Arctic ice core, I show an increasing trend of microplastics over time. I also observed a positive relationship between microplastics and organophosphate esters (a plastic additive), suggesting microplastics may act as a long-range transport pathway. In Chapter 4, I sampled snow from five sites at increasing distances from a local community. I observed a change in microplastic and polymer composition in sites closer to the local community suggesting that local sources of microplastics may also be important. In Chapter 5, I investigated the presence of microplastics and additive chemicals in wild-caught Arctic char (Salvelinus alpinus) and their habitat. Here, I show elevated concentrations of microplastics in Arctic char and their summer feeding habitat compared to previously reported observations. I also demonstrate translocation of microplastics to Arctic char. And finally, in Chapter 6, informed by observations in the previous chapters, I exposed larval fish to polyurethane, with and without chemical additives to assess the mechanisms of toxicity. Here, I show that the physical and chemical components of polyurethane affect growth and development, and that the physical particles may facilitate the bioaccumulation of plastic additive chemicals. Throughout my thesis, I highlight the importance of evaluating microplastics as a multi-dimensional contaminant - the physical and chemical properties may influence their fate, transport, and biological effects.Ph.D
Microfibers in a Freshwater Ecosystem: Sources, Fate, Effects, and Mitigation
No full textMicrofibers (anthropogenic fibers <5mm) are found in ecosystems around the world. Although microfibers have historically been lumped into the category of microplastics, they encompass a broader suite of contaminants. Microfibers reported in the environment are diverse including synthetic (e.g., polyester, nylon), semisynthetic (e.g., rayon, modal), and natural (e.g., cotton, wool) materials. Microfibers encompass more materials than microplastics, but microfibers are similar to microplastics in that they include chemical additives and accumulate ambient chemicals from the environment. Although there is some research on the prevalence, fate, and effects of synthetic (or plastic) microfibers, there are still many unknowns regarding the chemicals they may transfer, their environmental fate, and any potential toxic effects they may cause. Such research gaps are especially prevalent for non-plastic (or natural) microfibers.
My PhD research addresses these gaps. I examine the sources, fate, and ecological impacts of both plastic and non-plastic microfibers. I then investigate a mitigation strategy for microfiber capture relevant to a known source of microfiber pollution, washing machines. Overall, I find: many types of microfibers contaminate freshwater fishes, including lake trout (Salvelinus namaycush) and rainbow smelt (Osmerus mordax) (Chapter 2); cotton and polyester microfibers have similar effects on the benthic invertebrate, Chironomus dilutus (Chapter 3), but microfiber material type has different impacts on the bioaccumulation of polybrominated diphenyl ethers (PBDEs) and quantities of fatty acids in rainbow trout (Oncorhynchus mykiss) (Chapter 4); and washing machine filters are an effective mitigation strategy for reducing microfiber emissions at a community-scale (Chapter 5). An understanding of how a diverse suite of microfibers contaminate and affect biota can advance microplastics research and inform effective policy.Ph.D
Social Economic Aspects
No full textThis report provides an update and further assessment of the sources, fate and effects of microplastics in the marine environment, carried out by Working Group 40 (WG40) of GESAMP (The Joint Group of Experts on Scientific Aspects of Marine Protection). It follows publication of the first assessment report in this series in April 2015 (GESAMP 2015). The issue of marine plastic litter was raised during the inaugural meeting of the United Nations Environment Assembly (UNEA) in June 2014. Delegates from 160 countries adopted Resolution 1/6 on ‘Marine plastic debris and microplastics’ (Annex I). The resolution welcomed the work being undertaken by GESAMP on microplastics and requested the Executive Director of UNEP to carry out a study on marine plastics and microplastics. This was to be based on a combination of existing and new studies, including WG40. This provided the motivation for GESAMP to revise the original terms of reference to reflect both the request from UNEP to contribute to the UNEA study, and the key recommendations from the WG40 2015 report
The Global Plastic Cycle: Elucidating the Sources and Fate of Plastic Pollution in the Environment
No full textEvery minute, a garbage truck’s worth of plastic pollution enters the oceans. These plastic particles are transported through the ocean and accumulate in characteristic reservoirs or resting places, which is part of the “Global Plastic Cycle” (Chapter 1). To date, we do not have a good estimate of plastic emissions into the oceans. Moreover, reservoirs have not been quantified, impeding our ability to conduct a proper mass balance of plastic in the environment. The objective of my doctoral research is to fill these gaps to better characterize the Global Plastic Cycle. First, I aimed to develop a method to better quantify emissions of plastic pollution entering the environment, and eventually the ocean (Chapter 2). Second, I aimed to quantify major reservoirs of plastic pollution in the marine environment including the ocean floor (Chapter 3), coastlines (Chapter 4), and marine animal (Chapter 5) reservoirs. For my first research chapter (Chapter 2), I introduced a framework for tracking emissions of plastic pollution called an emissions inventory of plastic pollution, to help quantify how much plastic enters the environment and inform effective mitigation of plastic pollution at its source. We applied this framework to the City of Toronto, and estimated that 3,531-3,852 tonnes of plastic pollution are emitted from the city annually. For Chapters 3-5, I built regression models using data on plastic abundances in the environment to predict the total mass of plastic contained within major reservoirs of plastic pollution. I found that the ocean floor, coastlines, and sea turtle reservoirs contain 3-11 million metric tonnes, 6-7 kilotonnes, and 7-9 tonnes of plastic pollution, respectively, respectively. In my conclusion, I summarize the studies of reservoirs to date, and find that estimates within each reservoir span many orders of magnitude, showing that the quality of data is less than adequate for a proper mass balance to be conducted. My doctoral research has generated a tool for formal accounting of plastic emissions, it has helped to improve our understanding of the fate of plastic pollution after it enters the ocean, and it explores future work for elucidating the fate of plastic pollution in the marine environment.Ph.D
Research Gaps in the Study of Microplastics: Method Development for Raman Automation, and Examining Relationships between Ecological Traits and Anthropogenic Particle Ingestion in a Deep-sea Food Web
No full textMicroplastics and other anthropogenic microparticles are an emerging class of contaminants in marine ecosystems. I explore two research gaps within the field of microparticle pollution: one related to improving efficiency and accuracy of microparticle quantification, and another related to the fate of microparticles in food webs. First, I validated the use of a non-polymeric adhesive to improve automated spectroscopy methods, as well as tested subsampling strategies to improve quantification efficiency. Second, I characterized the amount and diversity of microparticles ingested by species from a deep-sea food web of Monterey Bay, California. I assessed differences in particle ingestion in the context of ecological traits including habitat, diet, feeding strategy, and body size. I determined that species who occupied the lower-mesopelagic and bathypelagic zones were associated with a less diverse assemblage of particle morphologies compared to epipelagic and upper-mesopelagic species suggesting that where an animal lives in the water column influences exposure.M.Sc
CORPORATE MANAGEMENT IN FEW MULTINATIONAL COMPANIES REPRESENTED IN ROMANIA
No full textThe paper contains the results of an interesting research done by the author in some multinational companies which have branches in Romania, mainly in Bucharest, Arad and Timisoara. The objective of the research paper was to find out some particular aspects of the corporate management taking into account some key variables like: corporate values, leadership style, strategic perspectives and communication. In order to do this research we have developed a special survey based on a questioner. The survey shown us how all these above mentioned variables are influencing the corporate management and how important is each of them within the management process. The results of these surveys gave us the possibility to find out the way in which corporate management is influencing and is influenced by the variables considered. Last part of the paper presents some conclusions of our survey and the most important changes which should be taken into account by the corporate management team members in order to be more efficient and effective in their work.corporate management, cultural values, leadership, strategic perspectives, communication
Assessing the Ecological Effects of Multiple Stressors in River and Stream Ecosystems
No full textFreshwater ecosystems are subjected to a multitude of stressors resulting from human population growth, urbanization, and climate change. One class of stressors facing freshwater ecosystems is contaminants (some of which are pollutants), which come from a variety of point and non-point sources (e.g., agriculture, wastewater, stormwater) and human activities (e.g., fishing, recreation). Despite widespread recognition that freshwater ecosystems are subject to multiple anthropogenic contaminants, there is still a need to understand their effects as a mixture, and at multiple levels of biological organization (i.e., sub-organismal to ecosystem-level effects). The goal of my doctoral research is to understand the sources, sinks, and ecological impacts of plastics and other chemical contaminants as a mixture, in the context of multiple stressors. I use both field and laboratory approaches to understand patterns of contamination and effects of stressors in two systems, one large estuary in Northern Vietnam, and a smaller, urbanized tributary in Toronto, Ontario, Canada. In my first two data chapters, I use observational field data to demonstrate that plastic (macroplastic and microplastics) and other contaminant stressors (anthropogenic debris, metals, polycylic aromatic hydrocarbons, road salt) are ubiquitous in the environment and are associated with human activities (e.g., fishing) and types of land-use (e.g., urban, roads). I then explore the ecological impacts of these contaminant mixtures using common ecological indices, community analysis, and a laboratory experiment. I leverage field data to demonstrate that elevated stressors are negatively associated with ecological effects (i.e., canopy cover, mangrove diameter, crab burrows, taxonomic diversity, incidence of tolerant taxa). Using an experimental approach, I demonstrate that, although exposure to some stressors leads to individual level mortality, the presence of mixtures does not worsen these effects. Collectively my research contributes to our understanding of the sources, fate, and ecological effects of multiple stressors, demonstrating the ways in which technologies and existing approaches can be adapted to take a more environmentally relevant approach to understand them. Future work should continue to investigate the impacts of locally relevant mixtures on local ecosystems to identify effects, monitor changes, and evaluate the efficacy of management and conservation efforts.Ph.D
Microplastics and Other Anthropogenic Debris in Fish and Potential Implications for Human Exposures
No full textMicroplastics are an inconspicuous environmental threat that have received considerable attention due to global contamination and potential adverse ecological and human health impacts. Recent studies demonstrate that microplastics are ingested by aquatic organisms and can cause physiological and toxicological damage. As a result, concerns have been raised by government agencies and the public regarding microplastics in seafood. First Nations communities around Lake Simcoe have also expressed concern regarding microplastic contamination in their fish. In response, I measured contamination levels in fish from Lake Simcoe and found 93.2% (N=44) contained anthropogenic debris, the majority (86.8%) being fibers. The size of the fish was positively correlated with the quantity of anthropogenic debris found. In addition, I tested the potential for microplastic translocation in laboratory fish to inform exposure routes to humans. No translocation of microplastics was observed, suggesting the consumption of fish fillets is likely not a significant exposure pathway to humans.M.Sc
Microplastics and Other Anthropogenic Debris in Fish and Potential Implications for Human Exposures
No full textMicroplastics are an inconspicuous environmental threat that have received considerable attention due to global contamination and potential adverse ecological and human health impacts. Recent studies demonstrate that microplastics are ingested by aquatic organisms and can cause physiological and toxicological damage. As a result, concerns have been raised by government agencies and the public regarding microplastics in seafood. First Nations communities around Lake Simcoe have also expressed concern regarding microplastic contamination in their fish. In response, I measured contamination levels in fish from Lake Simcoe and found 93.2% (N=44) contained anthropogenic debris, the majority (86.8%) being fibers. The size of the fish was positively correlated with the quantity of anthropogenic debris found. In addition, I tested the potential for microplastic translocation in laboratory fish to inform exposure routes to humans. No translocation of microplastics was observed, suggesting the consumption of fish fillets is likely not a significant exposure pathway to humans.M.Sc
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