This document proposes a research project to study plastic degradation by marine bacteria. The study would collect plastic samples from the ocean, isolate bacteria known to degrade hydrocarbons, and conduct experiments with plastics, seawater, bacteria, and copepods. The experiments aim to determine the bacteria's ability to degrade different types of plastics over time, identify degradation byproducts, and assess copepod survival under different conditions. The results could help understand plastic breakdown in oceans and evaluate whether bacterial activity produces toxic compounds or supports higher life forms.
This study compares zinc sulfide (ZnS) nanoparticles formed through bacterial sulfate reduction (biogenic) versus abiotic precipitation (abiogenic). Biogenic ZnS formed by Desulfovibrio desulfuricans bacteria were highly defective nanocrystals of mixed sphalerite and wurtzite structures between 4-12 nm. Abiogenic ZnS produced by titration or diffusion had poorly crystalline aggregates of randomly oriented crystals below 2-3 nm. Biogenic ZnS showed improved crystallinity compared to abiogenic samples, indicating bacterial metabolites promoted crystallization. This reveals differences in formation mechanisms between biogenic and abiogenic ZnS nanoparticles.
This dissertation by Aaron Alexander Jones examines the relationship between microbial community structure, function, and mineral surfaces in subsurface environments. Chapter 1 introduces the motivation and questions. Chapter 2 demonstrates that biofilm growth and microbial diversity are highly dependent on the type of mineral surface in nutrient-limited systems. Chapter 3 shows that mineral type controls up to 90% of phylogenetic diversity regardless of environmental conditions, indicating mineral selection is genetically ingrained. It also reveals shifts in community structure and function that impact geochemistry. Chapter 4 provides evidence that carbon isotope fractionation can be used to infer microbial community structure and function in sulfuric acid cave ecosystems.
TIE microplastics immersed in Muskegon Lake, Michiganjeanniekane
Toxicity analysis of three different types of microplastics - polyethylene, polypropylene, and polystyrene - immersed in the benthic and pelagic regions of Muskegon Lake, Michigan
This study examined how microplastics contaminated with persistent organic pollutants (POPs) like polycyclic aromatic hydrocarbons (PAHs) are taken up by marine snow aggregates. Microplastic beads were exposed to PAHs and introduced to seawater in rolling bottles to generate marine snow aggregates. Aggregates containing contaminated microplastics formed chain-like structures with high plastic content, unlike aggregates with uncontaminated plastics which contained more algae. The composition and structure of aggregates were analyzed using imaging software and flow cytometry. The results suggest POPs cause microplastics to incorporate differently into marine snow aggregates than uncontaminated plastics.
Effect of Concentration of Silver Nanoparticles on the Uptake of Silver from ...Agriculture Journal IJOEAR
— The bioavailability and uptake of silver from silver nanoparticles in soil was investigated. Two species of insects, Acheta domesticus and Tenebrio molitor, and two species of plants, Helianthus annuus and Sorghum vulgare, were exposed to a range of concentrations of silver nanoparticles in soil. Silver nanoparticles were charactrized by techniques including transmission electron microscopy, dynamic light scattering, and powder X-ray diffraction. The concentration of silver in insects and plants exposed to silver nanoparticles was measured using inductively coupled plasma-optical emission spectrometry. The results suggested an increase in the levels of silver in both insects and plants as a function of increasing concentrations of silver nanoparticles in soil. The translocation of silver to various parts of dicot plants such as stems and leaves was also observed. Such a result was not observed in the case of monocot plants. Results from this study suggests that silver nanoparticles would be available for uptake by insects and plants in terrestrial ecosystems.
This document discusses a study that investigated the effects of fine particulate organic matter (FPOM) size and quality on aquatic heterotrophic bacteria. The study generated four different size classes of maple and beech leaf particles of the same age through mechanical processing. It then measured the effects of particle size and quality on microbial community respiration, bacterial community structure, carbon and nitrogen content, and stable carbon and nitrogen isotope ratios. The main findings were that particle size had a strong effect on community respiration and carbon to nitrogen ratios, which decreased with smaller particle size, while bacterial community structure and carbon isotope ratios responded primarily to particle quality. Bacterial biomass was affected by interactions between particle size and quality. These results provide an unanticipated
1) The document examines variation in stomatal densities in Macroneuropteris scheuchzeri fossil samples from five locations in the Illinois Basin dating to 306-307 million years ago to understand paleoclimate conditions.
2) Data was collected by counting stomata and epidermal cells in boxes of defined areas on leaf peels and fragments from the samples. Average stomatal densities ranged from 7-13 per box across locations.
3) Preliminary results show modest variation in stomatal densities and indices between samples within locations, suggesting relatively stable climate conditions during this period based on the inverse relationship between stomatal features and atmospheric CO2 levels.
This study examined the ability of three bacterial strains - Streptomyces 1, Streptomyces 2, and Bacillus 1 - to precipitate calcite under alkaline conditions. The bacteria were cultured in different media formulations to determine which conditions promoted optimal calcite production while maintaining alkalinity. B4 media with varied carbon, nitrogen, and calcium sources was used. Results showed peptone-based media had higher pH but lower calcite precipitation than glucose-based media. Higher calcium concentration and an alternative media may be needed to further increase calcite formation under alkaline conditions.
This study compares zinc sulfide (ZnS) nanoparticles formed through bacterial sulfate reduction (biogenic) versus abiotic precipitation (abiogenic). Biogenic ZnS formed by Desulfovibrio desulfuricans bacteria were highly defective nanocrystals of mixed sphalerite and wurtzite structures between 4-12 nm. Abiogenic ZnS produced by titration or diffusion had poorly crystalline aggregates of randomly oriented crystals below 2-3 nm. Biogenic ZnS showed improved crystallinity compared to abiogenic samples, indicating bacterial metabolites promoted crystallization. This reveals differences in formation mechanisms between biogenic and abiogenic ZnS nanoparticles.
This dissertation by Aaron Alexander Jones examines the relationship between microbial community structure, function, and mineral surfaces in subsurface environments. Chapter 1 introduces the motivation and questions. Chapter 2 demonstrates that biofilm growth and microbial diversity are highly dependent on the type of mineral surface in nutrient-limited systems. Chapter 3 shows that mineral type controls up to 90% of phylogenetic diversity regardless of environmental conditions, indicating mineral selection is genetically ingrained. It also reveals shifts in community structure and function that impact geochemistry. Chapter 4 provides evidence that carbon isotope fractionation can be used to infer microbial community structure and function in sulfuric acid cave ecosystems.
TIE microplastics immersed in Muskegon Lake, Michiganjeanniekane
Toxicity analysis of three different types of microplastics - polyethylene, polypropylene, and polystyrene - immersed in the benthic and pelagic regions of Muskegon Lake, Michigan
This study examined how microplastics contaminated with persistent organic pollutants (POPs) like polycyclic aromatic hydrocarbons (PAHs) are taken up by marine snow aggregates. Microplastic beads were exposed to PAHs and introduced to seawater in rolling bottles to generate marine snow aggregates. Aggregates containing contaminated microplastics formed chain-like structures with high plastic content, unlike aggregates with uncontaminated plastics which contained more algae. The composition and structure of aggregates were analyzed using imaging software and flow cytometry. The results suggest POPs cause microplastics to incorporate differently into marine snow aggregates than uncontaminated plastics.
Effect of Concentration of Silver Nanoparticles on the Uptake of Silver from ...Agriculture Journal IJOEAR
— The bioavailability and uptake of silver from silver nanoparticles in soil was investigated. Two species of insects, Acheta domesticus and Tenebrio molitor, and two species of plants, Helianthus annuus and Sorghum vulgare, were exposed to a range of concentrations of silver nanoparticles in soil. Silver nanoparticles were charactrized by techniques including transmission electron microscopy, dynamic light scattering, and powder X-ray diffraction. The concentration of silver in insects and plants exposed to silver nanoparticles was measured using inductively coupled plasma-optical emission spectrometry. The results suggested an increase in the levels of silver in both insects and plants as a function of increasing concentrations of silver nanoparticles in soil. The translocation of silver to various parts of dicot plants such as stems and leaves was also observed. Such a result was not observed in the case of monocot plants. Results from this study suggests that silver nanoparticles would be available for uptake by insects and plants in terrestrial ecosystems.
This document discusses a study that investigated the effects of fine particulate organic matter (FPOM) size and quality on aquatic heterotrophic bacteria. The study generated four different size classes of maple and beech leaf particles of the same age through mechanical processing. It then measured the effects of particle size and quality on microbial community respiration, bacterial community structure, carbon and nitrogen content, and stable carbon and nitrogen isotope ratios. The main findings were that particle size had a strong effect on community respiration and carbon to nitrogen ratios, which decreased with smaller particle size, while bacterial community structure and carbon isotope ratios responded primarily to particle quality. Bacterial biomass was affected by interactions between particle size and quality. These results provide an unanticipated
1) The document examines variation in stomatal densities in Macroneuropteris scheuchzeri fossil samples from five locations in the Illinois Basin dating to 306-307 million years ago to understand paleoclimate conditions.
2) Data was collected by counting stomata and epidermal cells in boxes of defined areas on leaf peels and fragments from the samples. Average stomatal densities ranged from 7-13 per box across locations.
3) Preliminary results show modest variation in stomatal densities and indices between samples within locations, suggesting relatively stable climate conditions during this period based on the inverse relationship between stomatal features and atmospheric CO2 levels.
This study examined the ability of three bacterial strains - Streptomyces 1, Streptomyces 2, and Bacillus 1 - to precipitate calcite under alkaline conditions. The bacteria were cultured in different media formulations to determine which conditions promoted optimal calcite production while maintaining alkalinity. B4 media with varied carbon, nitrogen, and calcium sources was used. Results showed peptone-based media had higher pH but lower calcite precipitation than glucose-based media. Higher calcium concentration and an alternative media may be needed to further increase calcite formation under alkaline conditions.
Artifi cial wetlands are useful for wastewater treatment; however, relatively little is known of the effects of sewage on artifi cial wetland microbial community structure. Therefore, we assessed the effect of municipal sewage on microbial community diversity in surface water throughout an artifi cial wetland (Xiantao artifi cial wetland) treating municipal sewage. We analyzed the relationship between physicochemical parameters of surface water (i.e., Chemical Oxygen Demand (COD), Total Nitrogen (TN), Total Phosphorus (TP), and
NH4+-N) with microbial community structure (Illumina MiSeq sequencing followed by abundance indices). The results showed that the total microbial community in surface water was signifi cantly correlated with COD, TN, TP, and NH4
+-N (r = 0.764, 0.897, 0.883, 0.839, P < 0.05). In addition, the most abundant taxa were significantly correlated with COD (r = 0.803, P < 0.05). The relative abundance of rare operational taxonomic units in the more purifi ed water farther downstream was higher than in the polluted area, suggesting that rare groups were more sensitive to physicochemical parameters than abundant groups, and that the abundance of some bacteria could indirectly indicate the degree of aquatic pollution. Our results indicate that the responses of microorganisms in artificial wetlands to environmental conditions should be considered to ensure efficient treatment.
Settlement rates of invasive tunicates were observed over 4 weeks at different locations and depths in Pillar Point Harbor, California. Clod dissolution plates and settlement plates were used to measure flow rates and tunicate recruitment. Results showed no relationship between flow and settlement, but temperature increases, heavy algal growth, and predation on plates correlated with lower settlement. Further study of how temperature, competition, and predation impact recruitment is needed to better manage invasive tunicates.
Microplastics in marine organisms in KZN: A new conservation threat?MACE Lab
Refilwe Mofokeng, Gemma Gerber, Mathew Coote, Sipho Mkhize, Thembani Mkhize, Deborah Robertson-Andersson, Gan Moodley. Presented at the Symposium of Contemporary Conservation Practice 2015.
This thesis examines how small low-head dams alter stream conditions and influence leaf litter decomposition. In the first experiment, the author deployed leaf packs upstream, downstream, and within an intact, breached, and relict dam. After 8 weeks, decomposition rates were highest just downstream of the intact dam. Across sites, decomposition rates correlated negatively with conductivity. In a follow up study, the author tested if macroinvertebrate shredders or microbial colonization drove decomposition near an intact dam. Leaf packs were either exposed or enclosed in fine mesh bags. Decomposition was highest when shredders could access leaves, suggesting they drive rates near dams where conditions allow for shredder activity. The studies indicate intact low-head dams can
Fungal endophytes as priority colonizers initiating wood decompositionFeng Jin Liew, M.S.
1. The study tracked fungal communities as they transitioned from endophytes in living birch trees to saprophytes decomposing wood after tree death.
2. Birch stem sections were incubated in microcosms under controlled conditions, limiting colonization to existing endophytes or introducing additional fungi.
3. After 5 months of decomposition, communities were dominated by brown rot fungi that were originally present at low abundances as endophytes, matching the chemical signatures of brown rot decay in the wood residues.
First report on the use of gastropod shells by hermit crabs from the eastern ...debojyotyGhosh
This document reports on a study of hermit crab shell use along the coast of India. Researchers sampled gastropod shells and hermit crabs from intertidal zones in Bakkhali and Frazerganj, India over one year. They found two species of hermit crabs, Clibnarius padavensis and Clibnarius infraspinatus, used 21 different species of gastropod shells as habitats. Clibnarius padavensis showed a preference for Telescopium telescopium shells. Statistical analysis revealed a positive correlation between crab weight and shell weight. The study provides insight into the factors that influence hermit crabs' selection of gastropod shells as microhabitats
This document describes a molecular approach to studying transposon-host interactions in environmental samples without requiring culture. The author collected DNA samples from different aquatic environments and used PCR to amplify transposase genes and 16S rRNA gene fragments. Transposase primers were used as a "crib" to access genetic information from uncultured microorganisms by exploiting conserved regions in transposase. Junctions between transposase sequences and host DNA were amplified and sequenced. While a full transposon sequence was not retrieved, partial transposase gene sequences from Sulfolobus islandicus were obtained, validating the approach. Observations also indicated higher abundance of transposable elements in marine versus freshwater environments. With further optimization,
Dr. Xiomara Calderón-Colón is a Materials Scientist at the Johns Hopkins Applied Physics Laboratory.
She has a diverse educational background fusing materials science and chemistry by working across disciplines including nanomaterials, biomaterials and composite materials for protection and healthcare applications.
Currently, Dr. Calderón-Colón is a Principal Investigator, Project Manager, Task Lead, and Technical Contributor on multiple multidisciplinary projects.
Her contributions have been recognized with APL’s Invention of the Year Award, Women of Color Outstanding Technical Contribution in Industry Award, Publication Award and nominations for APL’s Invention of the Year & Government Purpose Invention.
She has three patents and more than 20 publications and presentations as first author or co-author.
Her presentation this evening highlights Multifunctional, Structured and Porous Material for Chemical and Biological Defense Applications.
There is a need to generate single materials that are low-cost and stable for protection, mitigation, and monitoring exposures to Chemical and Biological threats.
The fundamental understanding of interaction mechanisms is critical for the design and optimization of efficient, stable, and customizable platforms for Chemical and Biological defense applications.
This document summarizes a seminar on nanominerals and their formation. It defines nanominerals as naturally occurring minerals that are between 1-100 nanometers in size. Key points include:
- Nanominerals have unique quantum properties and behaviors compared to their bulk counterparts due to their small size.
- Common nanominerals include carbon nanotubes, zincite, rutile, and gold nanoparticles.
- Nanominerals form through both abiotic and biotic processes like weathering and bacterial activity.
- They are widely distributed in the atmosphere, oceans, groundwater, soils, and within living organisms.
- Characterization techniques like SEM, TEM, and AFM are used to study nan
The Influence of Vermiculite on the Uptake of Silver Nanoparticles in a Terre...Agriculture Journal IJOEAR
— The uptake of silver from silver nanoparticles in soil was investigated in the presence of increasing concentrations of Vermiculite, typical 2:1 clay. Two insect species, Acheta domesticus and Tenebrio molitor, and two plant species, Helianthus annuus and Sorghum vulgare, were exposed to silver nanoparticles in the presence of increasing concentrations of Vermiculite in soil. Silver nanoparticles were characterized using techniques including transmission electron microscopy, dynamic light scattering, and powder X-ray diffraction. The levels of silver in test species exposed to silver nanoparticles were measured using an inductively coupled plasma-optical emission spectrometer. An increase in the cation exchange capacity of soil was observed with the increase in the concentration of vermiculite in soil. The results suggested a decrease in the uptake of silver from silver nanoparticles in soil by Acheta domesticus as a function of increasing concentrations of Vermiculite in soil. No apparent trend was observed in the remaining species. Both plant species were found to accumulate silver in their roots. The translocation of silver to stems and leaves was observed in the case of Helianthus annuus. Results from this study suggest that the presence of Vermiculite in soil could possibly decrease the uptake of silver from silver nanoparticles.
1) The document discusses a study on the oxidation kinetics of 11 common organic contaminants in water treatment by ozone and hydroxyl radicals. The contaminants included various alcohols, aldehydes, ketones and ethers.
2) Five of the compounds were very efficiently oxidized by ozone, with rate constants of around 105 M–1s–1. Trihaloanisoles proved most resistant to ozone but were degraded by hydroxyl radicals.
3) The authors note hydroxyl radical treatment needs to be carefully applied to avoid producing excessive bromate ions from residual bromide salts.
This document discusses different types of plankton. It describes phytoplankton such as diatoms, dinoflagellates, coccolithophores and cyanobacteria. Diatoms are enclosed in silica cases and come in many shapes and sizes. Dinoflagellates can cause harmful algal blooms. Coccolithophores have scales and two flagella. Zooplankton include holoplankton which spend their whole lives as plankton, and meroplankton which are plankton temporarily. Examples given are copepods, ostracods and rotifers. The document also discusses using diatoms to help determine causes of death in forensic investigations.
Risk in the use of silver nanoparticles on humainPierre Basmaji
This document summarizes the risks associated with nanosilver toxicity and its effects on human health. It discusses how nanosilver is being used in many consumer products due to its antibacterial properties but that its small size and large surface area may increase its toxicity compared to bulk silver. The document outlines several potential health effects from nanosilver exposure including argyria (permanent skin discoloration), respiratory issues, gastrointestinal problems, kidney and liver damage, and cellular damage. It concludes that more research is needed to fully characterize nanosilver's health risks to humans.
A Novel Methodology for the Separation of Known Suspended Microplastics (<...MACE Lab
This document presents a novel methodology for separating microplastics (<500μm) from particulate organic matter (POM) in water samples. Current separation methods are inefficient at separating suspended microplastics and POM due to similarities in size and density. The developed method uses a two-phase separation where a non-polar solvent is added to draw microplastics into a separate immiscible layer, allowing removal without POM. Testing recovered over 90% of fluorescent polyethylene terephthalate and polypropylene microplastics added but only 1% of denser polyethylene terephthalate microbeads. This accurate separation method can be applied to experimental studies examining microplastic ingestion and effects in marine organisms.
Treatment of Domestic Wastewater Using Chemical Coagulation Followed by Geote...paperpublications3
Abstract: The emphasis of this paper is on the filtration performance of geotextiles. As we know treatment of wastewater has become an absolute necessity. An innovative cheap and effective method of purifying and cleaning wastewater before discharging into any other water systems is needed. Coagulation-flocculation is a chemical water treatment technique typically applied prior to sedimentation and filtration to enhance the ability of a treatment process to remove particles. Filtration is considered the most important solid-liquid separation process in water treatment, as well as in wastewater treatment. Geotextile are indeed textiles in the traditional sense, but they consist of synthetic fibers rather than natural ones such as cotton, wool, or silk. Thus bio degradation and subsequent short lifetime is not a problem. These synthetic fibers are made into flexible, porous fabrics by standard weaving machinery or are matted together in a random non-woven manner. Proper selection of geotextile filters plays a key role in achieving satisfactory filtration performance.
Wurzbacher, Grimmett, Bärlocher, 2016. Metabarcoding fungal diversity Ivan Grimmett
This document summarizes a study that characterized fungal communities on coarse particulate organic matter (CPOM) like leaves and fine particulate organic matter (FPOM) in a stream in Nova Scotia, Canada using metabarcoding. Maple leaves were exposed in the stream for 4 weeks and 4 FPOM size fractions were collected over the same period by filtration. Pyrosequencing of the samples identified a total of 821 fungal operational taxonomic units, with 726 exclusive to particle samples and 47 to leaf samples. The study aimed to shed light on fungal processing of organic matter in streams and broaden understanding of freshwater fungal diversity.
domestic rain water harvested water quality : an overviewBLESSY ALOSHIOUS
1) The document discusses factors that affect the quality of domestically harvested rainwater (DRWH). It outlines various studies that have examined microbiological and chemical contamination of DRWH systems.
2) Key factors discussed include the type and age of roofing materials, area and period of dry spells, rainfall intensity, storage media, and treatment methods. Studies have found higher levels of contamination in aged roofs and with increases in roof area and dry period length.
3) The document recommends technical approaches like first flush diverters and filters to improve water quality as well as financial support for household rainwater harvesting systems. Case studies examine the effects of roof age on metal contamination and evaluate a designed filtration system.
This document discusses the use of diatoms in forensic science to help determine cause of death in drowning cases. Diatoms are single-celled algae with glass cell walls that are found in different types and abundances depending on the water source. Their extraction from tissues and water samples, as well as comparison of diatom species found, can provide evidence to support or refute a drowning determination. The document outlines diatom extraction procedures, limitations of the technique, and presents three case studies where diatom analysis aided investigations.
Researchers from Black Hills State University are studying microbial life found deep underground at the Sanford Underground Research Facility. On an expedition to the 17 Ledge area at the 4850 foot level, the researchers encountered hot, humid conditions with temperatures of 95 degrees and 98% humidity. They collected samples from biofilms, pools of water, and growth on cavern walls. The samples were then analyzed at the new Black Hills State University Underground Campus to observe any living microorganisms using microscopy techniques. This allowed the researchers to see light-sensitive cells without needing to stain or kill the samples first. Their observations found possible fungi, rotifers, bacteria, and a gastrotrich.
Plastisphere is a man-made ecosystem based on Plastic debris in the ecosystem. This PPT describes the formation and importance of Plastisphere in an aquatic ecosystem.
Scientists Discover Thriving Colonies of Microbes in Ocean 'Plastisphere'olivierdylan
Scientists have discovered thriving colonies of over 1000 types of microbes living on tiny pieces of ocean plastic debris, known as the "plastisphere". These complex microbial communities have developed since the explosion of plastics in the oceans over the last 60 years. The microbes on the plastic are distinct from those in surrounding seawater, raising questions about how these plastic-based habitats could impact ocean ecosystems and microbial transport.
Artifi cial wetlands are useful for wastewater treatment; however, relatively little is known of the effects of sewage on artifi cial wetland microbial community structure. Therefore, we assessed the effect of municipal sewage on microbial community diversity in surface water throughout an artifi cial wetland (Xiantao artifi cial wetland) treating municipal sewage. We analyzed the relationship between physicochemical parameters of surface water (i.e., Chemical Oxygen Demand (COD), Total Nitrogen (TN), Total Phosphorus (TP), and
NH4+-N) with microbial community structure (Illumina MiSeq sequencing followed by abundance indices). The results showed that the total microbial community in surface water was signifi cantly correlated with COD, TN, TP, and NH4
+-N (r = 0.764, 0.897, 0.883, 0.839, P < 0.05). In addition, the most abundant taxa were significantly correlated with COD (r = 0.803, P < 0.05). The relative abundance of rare operational taxonomic units in the more purifi ed water farther downstream was higher than in the polluted area, suggesting that rare groups were more sensitive to physicochemical parameters than abundant groups, and that the abundance of some bacteria could indirectly indicate the degree of aquatic pollution. Our results indicate that the responses of microorganisms in artificial wetlands to environmental conditions should be considered to ensure efficient treatment.
Settlement rates of invasive tunicates were observed over 4 weeks at different locations and depths in Pillar Point Harbor, California. Clod dissolution plates and settlement plates were used to measure flow rates and tunicate recruitment. Results showed no relationship between flow and settlement, but temperature increases, heavy algal growth, and predation on plates correlated with lower settlement. Further study of how temperature, competition, and predation impact recruitment is needed to better manage invasive tunicates.
Microplastics in marine organisms in KZN: A new conservation threat?MACE Lab
Refilwe Mofokeng, Gemma Gerber, Mathew Coote, Sipho Mkhize, Thembani Mkhize, Deborah Robertson-Andersson, Gan Moodley. Presented at the Symposium of Contemporary Conservation Practice 2015.
This thesis examines how small low-head dams alter stream conditions and influence leaf litter decomposition. In the first experiment, the author deployed leaf packs upstream, downstream, and within an intact, breached, and relict dam. After 8 weeks, decomposition rates were highest just downstream of the intact dam. Across sites, decomposition rates correlated negatively with conductivity. In a follow up study, the author tested if macroinvertebrate shredders or microbial colonization drove decomposition near an intact dam. Leaf packs were either exposed or enclosed in fine mesh bags. Decomposition was highest when shredders could access leaves, suggesting they drive rates near dams where conditions allow for shredder activity. The studies indicate intact low-head dams can
Fungal endophytes as priority colonizers initiating wood decompositionFeng Jin Liew, M.S.
1. The study tracked fungal communities as they transitioned from endophytes in living birch trees to saprophytes decomposing wood after tree death.
2. Birch stem sections were incubated in microcosms under controlled conditions, limiting colonization to existing endophytes or introducing additional fungi.
3. After 5 months of decomposition, communities were dominated by brown rot fungi that were originally present at low abundances as endophytes, matching the chemical signatures of brown rot decay in the wood residues.
First report on the use of gastropod shells by hermit crabs from the eastern ...debojyotyGhosh
This document reports on a study of hermit crab shell use along the coast of India. Researchers sampled gastropod shells and hermit crabs from intertidal zones in Bakkhali and Frazerganj, India over one year. They found two species of hermit crabs, Clibnarius padavensis and Clibnarius infraspinatus, used 21 different species of gastropod shells as habitats. Clibnarius padavensis showed a preference for Telescopium telescopium shells. Statistical analysis revealed a positive correlation between crab weight and shell weight. The study provides insight into the factors that influence hermit crabs' selection of gastropod shells as microhabitats
This document describes a molecular approach to studying transposon-host interactions in environmental samples without requiring culture. The author collected DNA samples from different aquatic environments and used PCR to amplify transposase genes and 16S rRNA gene fragments. Transposase primers were used as a "crib" to access genetic information from uncultured microorganisms by exploiting conserved regions in transposase. Junctions between transposase sequences and host DNA were amplified and sequenced. While a full transposon sequence was not retrieved, partial transposase gene sequences from Sulfolobus islandicus were obtained, validating the approach. Observations also indicated higher abundance of transposable elements in marine versus freshwater environments. With further optimization,
Dr. Xiomara Calderón-Colón is a Materials Scientist at the Johns Hopkins Applied Physics Laboratory.
She has a diverse educational background fusing materials science and chemistry by working across disciplines including nanomaterials, biomaterials and composite materials for protection and healthcare applications.
Currently, Dr. Calderón-Colón is a Principal Investigator, Project Manager, Task Lead, and Technical Contributor on multiple multidisciplinary projects.
Her contributions have been recognized with APL’s Invention of the Year Award, Women of Color Outstanding Technical Contribution in Industry Award, Publication Award and nominations for APL’s Invention of the Year & Government Purpose Invention.
She has three patents and more than 20 publications and presentations as first author or co-author.
Her presentation this evening highlights Multifunctional, Structured and Porous Material for Chemical and Biological Defense Applications.
There is a need to generate single materials that are low-cost and stable for protection, mitigation, and monitoring exposures to Chemical and Biological threats.
The fundamental understanding of interaction mechanisms is critical for the design and optimization of efficient, stable, and customizable platforms for Chemical and Biological defense applications.
This document summarizes a seminar on nanominerals and their formation. It defines nanominerals as naturally occurring minerals that are between 1-100 nanometers in size. Key points include:
- Nanominerals have unique quantum properties and behaviors compared to their bulk counterparts due to their small size.
- Common nanominerals include carbon nanotubes, zincite, rutile, and gold nanoparticles.
- Nanominerals form through both abiotic and biotic processes like weathering and bacterial activity.
- They are widely distributed in the atmosphere, oceans, groundwater, soils, and within living organisms.
- Characterization techniques like SEM, TEM, and AFM are used to study nan
The Influence of Vermiculite on the Uptake of Silver Nanoparticles in a Terre...Agriculture Journal IJOEAR
— The uptake of silver from silver nanoparticles in soil was investigated in the presence of increasing concentrations of Vermiculite, typical 2:1 clay. Two insect species, Acheta domesticus and Tenebrio molitor, and two plant species, Helianthus annuus and Sorghum vulgare, were exposed to silver nanoparticles in the presence of increasing concentrations of Vermiculite in soil. Silver nanoparticles were characterized using techniques including transmission electron microscopy, dynamic light scattering, and powder X-ray diffraction. The levels of silver in test species exposed to silver nanoparticles were measured using an inductively coupled plasma-optical emission spectrometer. An increase in the cation exchange capacity of soil was observed with the increase in the concentration of vermiculite in soil. The results suggested a decrease in the uptake of silver from silver nanoparticles in soil by Acheta domesticus as a function of increasing concentrations of Vermiculite in soil. No apparent trend was observed in the remaining species. Both plant species were found to accumulate silver in their roots. The translocation of silver to stems and leaves was observed in the case of Helianthus annuus. Results from this study suggest that the presence of Vermiculite in soil could possibly decrease the uptake of silver from silver nanoparticles.
1) The document discusses a study on the oxidation kinetics of 11 common organic contaminants in water treatment by ozone and hydroxyl radicals. The contaminants included various alcohols, aldehydes, ketones and ethers.
2) Five of the compounds were very efficiently oxidized by ozone, with rate constants of around 105 M–1s–1. Trihaloanisoles proved most resistant to ozone but were degraded by hydroxyl radicals.
3) The authors note hydroxyl radical treatment needs to be carefully applied to avoid producing excessive bromate ions from residual bromide salts.
This document discusses different types of plankton. It describes phytoplankton such as diatoms, dinoflagellates, coccolithophores and cyanobacteria. Diatoms are enclosed in silica cases and come in many shapes and sizes. Dinoflagellates can cause harmful algal blooms. Coccolithophores have scales and two flagella. Zooplankton include holoplankton which spend their whole lives as plankton, and meroplankton which are plankton temporarily. Examples given are copepods, ostracods and rotifers. The document also discusses using diatoms to help determine causes of death in forensic investigations.
Risk in the use of silver nanoparticles on humainPierre Basmaji
This document summarizes the risks associated with nanosilver toxicity and its effects on human health. It discusses how nanosilver is being used in many consumer products due to its antibacterial properties but that its small size and large surface area may increase its toxicity compared to bulk silver. The document outlines several potential health effects from nanosilver exposure including argyria (permanent skin discoloration), respiratory issues, gastrointestinal problems, kidney and liver damage, and cellular damage. It concludes that more research is needed to fully characterize nanosilver's health risks to humans.
A Novel Methodology for the Separation of Known Suspended Microplastics (<...MACE Lab
This document presents a novel methodology for separating microplastics (<500μm) from particulate organic matter (POM) in water samples. Current separation methods are inefficient at separating suspended microplastics and POM due to similarities in size and density. The developed method uses a two-phase separation where a non-polar solvent is added to draw microplastics into a separate immiscible layer, allowing removal without POM. Testing recovered over 90% of fluorescent polyethylene terephthalate and polypropylene microplastics added but only 1% of denser polyethylene terephthalate microbeads. This accurate separation method can be applied to experimental studies examining microplastic ingestion and effects in marine organisms.
Treatment of Domestic Wastewater Using Chemical Coagulation Followed by Geote...paperpublications3
Abstract: The emphasis of this paper is on the filtration performance of geotextiles. As we know treatment of wastewater has become an absolute necessity. An innovative cheap and effective method of purifying and cleaning wastewater before discharging into any other water systems is needed. Coagulation-flocculation is a chemical water treatment technique typically applied prior to sedimentation and filtration to enhance the ability of a treatment process to remove particles. Filtration is considered the most important solid-liquid separation process in water treatment, as well as in wastewater treatment. Geotextile are indeed textiles in the traditional sense, but they consist of synthetic fibers rather than natural ones such as cotton, wool, or silk. Thus bio degradation and subsequent short lifetime is not a problem. These synthetic fibers are made into flexible, porous fabrics by standard weaving machinery or are matted together in a random non-woven manner. Proper selection of geotextile filters plays a key role in achieving satisfactory filtration performance.
Wurzbacher, Grimmett, Bärlocher, 2016. Metabarcoding fungal diversity Ivan Grimmett
This document summarizes a study that characterized fungal communities on coarse particulate organic matter (CPOM) like leaves and fine particulate organic matter (FPOM) in a stream in Nova Scotia, Canada using metabarcoding. Maple leaves were exposed in the stream for 4 weeks and 4 FPOM size fractions were collected over the same period by filtration. Pyrosequencing of the samples identified a total of 821 fungal operational taxonomic units, with 726 exclusive to particle samples and 47 to leaf samples. The study aimed to shed light on fungal processing of organic matter in streams and broaden understanding of freshwater fungal diversity.
domestic rain water harvested water quality : an overviewBLESSY ALOSHIOUS
1) The document discusses factors that affect the quality of domestically harvested rainwater (DRWH). It outlines various studies that have examined microbiological and chemical contamination of DRWH systems.
2) Key factors discussed include the type and age of roofing materials, area and period of dry spells, rainfall intensity, storage media, and treatment methods. Studies have found higher levels of contamination in aged roofs and with increases in roof area and dry period length.
3) The document recommends technical approaches like first flush diverters and filters to improve water quality as well as financial support for household rainwater harvesting systems. Case studies examine the effects of roof age on metal contamination and evaluate a designed filtration system.
This document discusses the use of diatoms in forensic science to help determine cause of death in drowning cases. Diatoms are single-celled algae with glass cell walls that are found in different types and abundances depending on the water source. Their extraction from tissues and water samples, as well as comparison of diatom species found, can provide evidence to support or refute a drowning determination. The document outlines diatom extraction procedures, limitations of the technique, and presents three case studies where diatom analysis aided investigations.
Researchers from Black Hills State University are studying microbial life found deep underground at the Sanford Underground Research Facility. On an expedition to the 17 Ledge area at the 4850 foot level, the researchers encountered hot, humid conditions with temperatures of 95 degrees and 98% humidity. They collected samples from biofilms, pools of water, and growth on cavern walls. The samples were then analyzed at the new Black Hills State University Underground Campus to observe any living microorganisms using microscopy techniques. This allowed the researchers to see light-sensitive cells without needing to stain or kill the samples first. Their observations found possible fungi, rotifers, bacteria, and a gastrotrich.
Plastisphere is a man-made ecosystem based on Plastic debris in the ecosystem. This PPT describes the formation and importance of Plastisphere in an aquatic ecosystem.
Scientists Discover Thriving Colonies of Microbes in Ocean 'Plastisphere'olivierdylan
Scientists have discovered thriving colonies of over 1000 types of microbes living on tiny pieces of ocean plastic debris, known as the "plastisphere". These complex microbial communities have developed since the explosion of plastics in the oceans over the last 60 years. The microbes on the plastic are distinct from those in surrounding seawater, raising questions about how these plastic-based habitats could impact ocean ecosystems and microbial transport.
This document outlines a study on microplastic pollution in central Virginia freshwater ecosystems. The author aims to characterize microplastic pollution by collecting crayfish from local streams and examining their digestive tracts, gill filaments, and surrounding waters. Preliminary results found possible microplastic particles in the digestive tracts of two crayfish. A follow up tank study found fibers entrapped in the gill filaments of some crayfish. The author concludes this study provides baseline data on microplastic pollution in freshwater invertebrates and environments. Future work could examine microplastic biomagnification in higher trophic levels and their associated microbiota.
Slides from the Deschutes Land Trust's Nature Night presentation by Dr. Susanne Brander, researcher at Oregon State University considering the impacts of microplastic pollution on our environment.
Microplastics were found to enter the organs of scallops within six hours of exposure according to a new study. The study used radio-labeled nanopolystyrene to trace the life cycle of microplastics in scallops. It took 14 days for 20 nanometer microplastics and 48 days for 250 nanometer microplastics to leave the scallop's system. This raises concerns about the speed at which microplastics enter organisms and their potential effects on health as they may accumulate in the food chain. More research is still needed to understand the health risks but it highlights the importance of reducing plastic consumption.
The year 2018 has been all about plastic. We reported on the Starbucks announcement to phase out plastic straws by 2020 and talked about everything from SC Johnson's commitment to eliminate plastic by 2025 to the negative health effects of plastic straws. We clearly weren't the only ones with plastic on our minds, as Collins Dictionary named "single-use" the word of the year.
And it's all for good reason because among the many negative effects of excessive plastic consumption, microplastic might be making its way into our seafood, according to a new study.
This document summarizes the current state of knowledge around microplastics and their trophic transfer in aquatic ecosystems. It outlines background information on microplastics and their sources. It then reviews several case studies that demonstrate trophic transfer of microplastics between invertebrates, fish, and top predators like seals. The studies found microplastics accumulate at higher trophic levels. The document concludes by identifying key knowledge gaps and recommending future research focus on effects of microplastics on human health and standardizing detection methods, while promoting efforts to reduce plastic use.
This document discusses the role of biodegradable products in environmental sustainability. It begins by defining biodegradation as the breakdown of organic matter by microorganisms like bacteria and fungi. It then discusses how biotechnology can produce sustainable alternatives to polluting materials through biological processes. The document also examines the three stages of biodegradation - biodeterioration, biofragmentation, and assimilation. It provides timeframes for common materials to biodegrade in both terrestrial and marine environments. Finally, it discusses the environmental and social impacts of non-biodegradable pollution, such as threats to wildlife health, increased cleanup costs, and effects on coastal economies that rely on ecotourism.
The intern helped with a project that examined plastic pollution in the Chollas Creek watershed in San Diego. To understand the sources, pathways, and fates of plastic pollution, the intern:
1) Conducted trash surveys along the creek to identify common plastic items like bags and wrappers.
2) Tagged and tracked plastic bags through the watershed during rain events to see how plastic moves through the system.
3) Dissected fish from San Diego Bay to see if they had ingested microplastics, which were found in two of the three species.
The results will help educate the public on plastic pollution and the need for better watershed management.
Microplastics, small pieces of plastic, less than 5 mm (0.2 inches) in length, that occur in the environment as a consequence of plastic pollution. Microplastics are present in a variety of products, from cosmetics to synthetic clothing to plastic bags and bottles. Many of these products readily enter the environment in wastes.
Plastic pollution could we have solved the problem nearly 50 years ago HaulTail
Scientists have been studying plastic pollution for nearly 50 years, with initial research in the early 1970s finding plastic particles in the ocean and seabirds. However, the risks of plastic were not well publicized until recently. If the findings of early researchers had been addressed sooner, billions of tons of plastic waste may have been prevented from polluting the environment. The plastic industry attempted to influence public perception and push recycling as a solution rather than reducing plastic production and usage. Growing social media coverage of the impacts of plastic pollution has brought greater awareness to issues scientists have been documenting for decades.
The Vertical Distribution of Bouyant Plastics at SeaKimberly Noble
The document summarizes a study that used a new multi-level trawl to sample microplastics from the air-sea interface to a depth of 5 meters in the North Atlantic Gyre. The study found that plastic concentrations decreased exponentially with depth and that decay rates were lower when sea conditions were rougher. Smaller plastic pieces had lower rise velocities and were more susceptible to vertical transport, resulting in greater depth decays for plastic mass concentration than numerical concentration. The study provides new data on the vertical distribution and transport of microplastics in the upper water column.
(a) Ecosystems contain complex networks of interactions between organisms and their environment. (b) Organisms fall into different ecological roles including producers, consumers, and decomposers. Producers like plants make their own food through photosynthesis, consumers eat other organisms, and decomposers break down waste and dead material. (c) These roles are interconnected as one organism's waste becomes a resource for others, fueling nutrient cycling within the ecosystem.
Toxic Plastic Trash Drift in the North Pacific Subtropical Gyre Final PaperKameron Johnson
The document discusses plastic pollution in the North Pacific Subtropical Gyre. It notes that this region currently has the highest accumulation of microplastics compared to other subtropical gyres. The plastic debris comes from various sources like land pollution from North America, China, and Japan as well as lost or discarded fishing nets. Microplastics are ingested by marine life and can accumulate toxins, entering the food chain. More research is needed to understand the long term impacts on ecosystems and potential policy solutions to address plastic pollution at its source.
This project examined how beach sand composition and tide levels affect the size and age distribution of butter clams. Samples were taken from beaches with varying elevations and sieved to determine sand composition. Statistical analysis found significant differences in clam age and size based on tide level, but not sand composition. The oldest clams were found at higher tide levels, while the youngest were at extreme high and low levels. This data on clam habitat requirements can inform sustainable harvest and farming strategies.
This document is a student thesis submitted by Noelle Dunne that examines microplastic ingestion by dab fish (Limanda limanda) off the west coast of Ireland. The study found that 41% of the 87 fish examined contained microplastics in their gastrointestinal tracts, with an average of 2.2 pieces of plastic per fish. Fibres made up 95% of the plastics found. Larger fish and females contained more plastics. The study contributes to understanding of microplastic ingestion in fish and its potential long-term impacts.
Coastal marine ecosystem scientific paper swissmitchick
The document summarizes a study assessing the macrobenthic flora and fauna in the intertidal area of Dalipuga Beach in Iligan City, Philippines. Two 1-square-meter quadrats were placed in the transect line to analyze species composition. Only one algae species (Phaeophyta) was found in the first quadrat, while the second quadrat contained both algae and seagrass. Water temperature was 26-27°C, soil temperature was 25-26°C, humidity was 26%, sediment was sand and gravel, and pH and salinity were normal. No macrobenthic fauna was found.
Utilization of Multiple Habitat Sampling Protocol for Macroinvertebrates as Indicators of Water
Quality in Stream Ecosystem in Lawis,
Buruun, Iligan City
Need help with some fairly simple biology questions.1. What is che.pdffeetshoemart
Need help with some fairly simple biology questions.
1. What is chemical selection?
2. How do paleontologists determine the age of a fossil?
3. Define evolution. What is the difference between microevolution and macroevolution?
Solution
1. Chemical selection occurs when a chemical within a mixture has special properties or
advantages that cause it to increase in number compared to other chemicals in the mixture.
Initially, scientist speculate that the special properties that enabled certain RNA molecules to
undergo chemical selection were its ability to self-replicate and to perform other enzymatic
functions.
2. Scientists combine several well-tested techniques to find out the ages of fossils. The most
important are relative dating, in which fossils and layers of rock are placed in order from older to
younger, and radiometric dating, which allows the actual ages of certain types of rock to be
calculated.
Relative Dating. Relative dating is the science of determining the relative order of past events
(i.e., the age of an object in comparison to another), without necessarily determining their
absolute age, (i.e. estimated age). In geology, rock or superficial deposits, fossils and lithologies
can be used to correlate one stratigraphic column with another.
Fossils are found in sedimentary rocks that formed when eroded sediments piled up in low-lying
places such as river flood plains, lake bottoms or ocean floors. Sedimentary rock typically is
layered, with the layers derived from different periods of sediment accumulation. Almost any
place where the forces of erosion - or road crews - have carved through sedimentary rock is a
good place to look for rock layers stacked up in the exposed rock face.
If we look at a layer cake, we will that the layer at the bottom was the first one the baker put on
the plate, and the upper ones were added later. In the same way, geologists figure out the relative
ages of fossils and sedimentary rock layers; rock layers, and the fossils they contain, toward the
bottom of a stack of sediments are older than those found higher in the stack.
Radiometric Dating. The use of radiometric dating was first published in 1907 by Bertram
Boltwood. Radiometric dating or radioactive dating is a technique used to date materials such as
rocks or carbon, in which trace radioactive impurities were selectively incorporated when they
were formed. The method compares the abundance of a naturally occurring radioactive isotope
within the material to the abundance of its decay products, which form at a known constant rate
of decay. Now it the principal source of information about the absolute age of rocks and other
geological features, including the age of fossilized life forms
Radiocarbon dating: It involves determining the age of an ancient fossil or specimen by
measuring its carbon-14 content. Carbon-14, or radiocarbon, is a naturally occurring radioactive
isotope that forms when cosmic rays in the upper atmosphere strike nitrogen molecu.
Similar to OBrien_ProjectProposal_UWP104Escn4 (20)
Need help with some fairly simple biology questions.1. What is che.pdf
OBrien_ProjectProposal_UWP104Escn4
1. Jacob O’Brien
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Analytical introduction
I chose the Scripps institute as a potential sponsor for this project proposal. In class, when
we had the opportunity to look up sponsors, I found a researcher who would be a perfect match.
Bianca Brahamsha is a researcher with interests including biology and physiology of
cyanobacteria, which are some of the main candidates for plastic degradation. Bacterial diversity
and predator prey interactions are also pivotal in understanding the potential in these research
systems. I am writing a proposal in the format that Scripps suggests. I put why my candidacy
should be considered at the very end of the paper with real life accomplishments that would
probably help in their consideration.
As far as the paper goes, I have really tried to accomplish the ideas we have discussed in
class. The two things that I have really tried to work on this quarter are being specific and paying
close attention to my word choice so that it is as clear and concise as possible. I put forth a lot of
effort into rewriting sentences that were wordy to make them clearer. This has proven difficult,
as I have been writing for years without the knowledge I have obtained from this class. Habits
don’t break so easily in 10 weeks, but I hope that you will see that my writing has improved
since the beginning of the quarter.
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Introduction
According to a report by Plastics Europe, 288 million tons of plastic were produced in
2012 [1]. Much of this ends up in undesirable locations including the oceans. Researchers wish
to find out how much plastic ends up in the oceans because plastics cause damage to the
environment via absorption of toxic compounds and ingestion by marine animals [1]. Ingestion
by higher trophic level organisms is not the ultimate fate for many plastics in the oceans.
Microorganisms exist in complex communities on plastic pieces [2]. Some microorganisms
congregate on the plastics increasing the density and causing them to sink [2]. Others have even
been shown to consume some types of plastic for energy [3, 4, 5]. One day, it may be possible to
take advantage of these microbes to help solve a growing plastic problem in the oceans.
Investigators hypothesize; enrichment of known hydrocarbon degrading microbial communities
by increasing bacterial numbers will increase degradation efficiency. It is also hypothesized that
the byproducts of this degradation will contain toxic compounds in measurable levels.
Background
Estimation of Total Plastics
Eriksen et. al, conducted a large scale experiment to estimate the total plastics present in
the World’s oceans by measuring the number density of different sized plastics. Until their
investigation, the only sampling completed has been on microplastics.
Investigators separated and counted plastics based on their size. “We compared plastic
pollution levels between oceans and across four size classes: 0.33–1.00 mm (small
microplastics), 1.01–4.75 mm (large microplastics), 4.76–200 mm (mesoplastic), and >200 mm
(macroplastic) [1].” Observations were conducted in two ways. First, a net with a mesh size of
0.33 mm was towed behind a boat for between 15 and 60 minutes to collect plastics on and just
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below the surface of the water [1]. This method was utilized 680 times. Then, plastics were
counted, measured, and weighed. Total density was determined by dividing total number by total
area trawled. Second, investigators observed over one side of a boat noting visible debris during
observation times. Observations were conducted 891 times. With the data collected, investigators
entered them into a model to predict a total oceanic distribution of plastics. The model included
important variables to increase the accuracy of the predictions.
The data revealed, conservatively, 5.25 trillion plastic particles weighing 268,940 tons
currently floating in the oceans [1]. Most density estimates were between 1000-100,000 plastic
pieces per square kilometer [1]. Microplastics were the most numerous and the macroplastics
were the heaviest. Most of the plastics were concentrated in the subtropical oceanic gyres [1].
These data are enlightening, but they only scratch the surface. Ultimately, most plastic does not
stay at or near the surface, so what happens to it?
Micro-organismal Association with Plastics
Microorganisms associate with plastics in marine environments. Processes they are
involved in include protection from ultraviolet rays, decreasing buoyancy, attracting higher
trophic level organisms, or even accelerating degradation [3]. One of the main ways plastics
degrade is through photo-degradation. Ultra violet rays break plastics into smaller and smaller
pieces. Some bacteria form a biofilm layer, which promote conducive growing environments.
These biofilms have inherent ultraviolet protection [3]. When enough bacteria congregate on a
piece of plastic, they change the buoyancy of the plastic causing it to sink [3]. Some bacteria
even utilize hydrocarbons as energy sources to break down the plastics [2].
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Carson et al. were interested in finding out what types of bacteria were present on plastics
and in what numbers. They were also interested in finding out how these variables differed based
on variable factors of both the ocean (time, temperature, location) and the plastics (size,
composition). A path was set up from Hawaii to Vancouver, Canada where 17 separate trawl
samples were conducted. A mesh size of 0.33 mm was deployed for one hour at a constant speed
to keep separate measurements equal.
To determine what organisms were present on the samples, plastic pieces were first
rinsed clean of all water and then prepared for scanning electron microscopy. A random degree
of vision was chosen to get an unbiased representation of the samples. Then the microorganisms
were identified based on physical properties. Because of the way samples were preserved, it was
impossible to identify the microorganisms’ species accurately. Identification of the
microorganisms was limited to visual characteristics. Plastic polymer types were also identified.
Every piece of plastic of the 83 samples contained microorganisms. Rod shaped bacteria
and diatoms appeared most frequently on the plastics. Other bacteria types were found
significantly less frequently [3]. The most abundant plastic type was polyethylene. Styrofoam,
which is a form of polystyrene, did harbor significantly more bacillus bacteria compared to the
other plastic types. Surface roughness played a role in harboring diatomaceous life. Samples that
were more rough contained more diatoms. According to the findings, most diversity stems from
the size of the particles compared to the other variables [3]. Now that the general types of
microorganisms that exist on different types of marine plastic debris have been identified, the
next step is to find out more details about these organisms.
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Reisser et al, performed a similar experiment of marine plastic collection. Investigators
collected plastic and identified microbes via scanning electron microscopy. An important detail
observed by researchers was the identification of pits with the shape of these microorganisms in
the plastic debris [6]. These microtextures were indicative of plastic utilization by bacteria.
Larger sizes of plastics as well as these pits allow the possibility for more diverse microbial
colonization. These pits may be important to facilitate further degradation.
Finding Bacteria Capable of Hydrocarbon Degradation
Because the close identification of microorganisms existing on marine plastic pieces was
lacking, Zettler et al, set out to identify these communities. Researchers hypothesized that the
communities existing on plastic are significantly different from those in the surrounding seawater
[2]. Data were collected in a similar fashion to the previous experiment [3], but the samples were
preserved differently to identify the organisms using molecular evidence. Samples were prepared
for scanning electron microscopy as well as Raman spectroscopy, which reveal the composition
of plastics. Investigators extracted DNA from samples, amplified, sequenced, and compared to
known DNA sequences. This process enabled investigators to identify specific bacterial
organisms.
As in the last experiment, most of the plastics identified were polyethylene and
polypropylene which are both common in packaging and single-use applications [2]. The
communities inhabiting the plastics were indeed different compared to the surrounding seawater.
Filamentous cyanobacteria were the second most common morphotype on plastics, but were
completely absent from seawater samples [2]. Diatoms were also present in large numbers on
these plastic pieces. Diatoms are an important find, because they significantly alter plastic
density causing the pieces to sink. An interesting find was the presence of planktonic protists not
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known to associate with any substrates [2]. Investigators observed over a thousand species from
a single fragment of plastic, but most importantly was the identification of some species known
to degrade hydrocarbons. Members of the genera Phormidium, Pseudomonas, and Hyphomonas
were found in significant numbers on plastic debris [2]. All three of these groups have been
shown to be able to degrade hydrocarbons [2]. Members closely related to these three groups
were also identified on debris, which may be another focal point on future studies to determine
the significance of plastic degradation in marine systems.
Hydrocarbon Degrading Capabilities
High-density polyethylene (HDPE) represents up to 64% of synthetic plastics produced
[4]. This type of plastic is an important study point because of its widespread and diverse usage.
Balasubramanian et al, collected HDPE pieces found in the Gulf of Mannar. Investigators
inoculated samples with a synthetic media to facilitate growth of desirable bacteria. After an
incubation period of 12 weeks, bacteria samples were purified and screened for HDPE-degrading
bacteria [4]. To determine the efficiency of bacterial degradation, investigators incubated
samples with a predetermined amount of HDPE. The samples were then washed, dried, and
weighed to determine how much plastic was degraded. Investigators performed a bacterial
adhesion to hydrocarbon assay to determine hydrophobicity levels of these samples. This test
reveals the attraction of bacteria to plastic samples via light spectroscopy. Based on
hydrophobicity, comes the viability of bacterial biofilm. A specific test reveals the presence of a
viable biofilm. Molecular probes attach to cells and fluoresce different colors based on cell
condition. Cells glow red if dead and green if alive. This test allowed investigators to determine
if a biofilm was present on HDPE samples after a 30 day incubation period. Because of the
difficulty involved in accurately measuring population density within biofilms, investigators
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used a more reliable method and estimated bacterial counts by measuring present protein levels.
These proteins were measured and compared to known amounts to determine relative amounts of
bacteria present.
In the experiments, investigators tested 15 different strains of bacteria. Two of the 15
strains were capable of degrading hydrocarbons as the only source of energy [4]. One genus,
Pseudomonas, has been identified in previous studies. The other bacterium, Arhtrobacter, was
not previously identified in reviewed literature. After a 30 day incubation period, there was a
significant decrease in plastic mass. A decrease of 12 percent by Pseudomonas and 15 percent by
Arthrobacter is a promising result. According to the hydrophobicity test, Pseudomonas had a
higher affinity to the plastic, which is interesting because one would think having a higher
affinity would equate to a better degradation coefficient.
Harshvardhan et al conducted a very similar experiment as the one reviewed previously.
One major difference between the two is the type of plastic evaluated. In this experiment, low-
density polyethylene (LDPE) was evaluated. Sixty bacterial samples were evaluated with similar
techniques including identification, hydrophobicity, biofilm viability, and degradation ability. Of
the 60 samples, three of them were identified as capable of degrading the LDPE [5]. The three
useful bacteria identified are Kocuria palustris, Bacillus subtilis, and Bacillus pumilus. The
degradation capabilities of these three bacteria was significantly less than those degrading the
high-density polyethylene with between 1 and 2 percent degradation over a 30 day period. This
is an interesting find, because one would think that with lower density bonds in the plastic,
bacteria would have an easier time utilizing it as an energy source.
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Materials and Methods
The vessel R/V New Horizon, capable of open ocean missions, will be utilized to collect
samples in the Pacific Subtropical Gyre. Samples will be collected via a net with a mesh size of
30μm to capture large and small plastics. Once sufficient samples have been collected, they will
be stored until bacteria will be isolated. Specific members from the genera Phormidium,
Pseudomonas, Hyphomonas, Kocuria, and Bacillus are the target bacteria because of their
potential to degrade hydrocarbons [2, 4, 5]. To isolate bacteria, small samples of seawater with
the plastics will be centrifuged at low g-forces so as to not kill any bacteria, but at high enough
forces to separate them from the plastic. A sterile loop with an approximately 10μl storage
capacity will be dipped into the centrifuged sample to collect suspended bacteria. Next,
investigators will streak plate agar enriched with a mineral medium containing polyethylene and
polypropylene molecules as the only carbon source, because this has been previously shown to
facilitate growth of bacteria capable of degrading hydrocarbons [7]. This method will eliminate
undesired bacteria and ease the identification of desired bacteria. Because the identification is not
guaranteed, the plating technique will be performed several times per sample from several
different samples until desired bacteria are present. Once colonies are isolated, they will be re
streaked to obtain pure isolates.
The first round of experimental samples will be created using one liter of sterile seawater,
sufficient nutrients to support growth, and 50mg each of polypropylene, high-density
polyethylene, and low-density polyethylene. A total of 12 samples will be prepared. One sample
will be a control with only plastics and sterile seawater. One more control sample will contain
plastics, seawater, and an inoculation of bacteria not known to degrade hydrocarbons. The
remaining 10 samples will be inoculated with equal amounts of the four different experimental
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bacteria. All samples will be exposed to the same conditions of 12°C to emulate ambient oceanic
temperatures, a 10 hour day 14 hour night cycle to simulate natural sunlight conditions, and a
constant motion to simulate wave action. After a 30 day testing period, plastics from the samples
will be removed, sterilized, dried and weighed to determine the amount of degradation of each
type. Water from the 10 samples will be mixed thoroughly before exposed to mass spectrometry.
Spectrometry will allow investigators to determine molecular compounds present in the sample
likely to be byproducts of the degradation process. Deciphering the composition of these
compounds will reveal benign versus toxic molecules present.
The second and third round of experiments will be set up almost identical to the first. For
the second round, the same 12 samples will be set up as before only this time adding in a set
amount of copepods to each. The third and final round of experiments will be the same as round
two, except all 12 samples will be inoculated with greatly increased numbers of bacteria. The
samples will undergo the same physical conditions and after a 30-day period, copepod survival
will be evaluated.
Expected Results
After the testing period, a decrease in plastic mass is expected in all experimental groups
compared to control groups. The highest amounts of degradation compared to controls are likely
to take place in the samples inoculated with the most plastic degrading bacteria. This may not be
the case however; too many bacteria may slow the degradation process. Bacteria may be limited
by factors including space, decreasing degradation. It is expected to see a larger decrease in mass
of HDPE compared to LDPE as that is what is shown in previous studies [5]. Because of the
physical properties of polypropylene, which are similar to HDPE, less degradation is expected
compared to either type of polyethylene. However, it is entirely possible polypropylene will have
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higher rates of degradation. It is reasonable to expect this because bacteria are more efficient at
degrading HDPE compared to LDPE.
As well as recording plastic degradation, investigators will also measure copepod
survival in each sample. The lowest survival is expected to be the control samples with only
plastics and seawater, because the lack of sustenance for the copepods. The highest survival will
most likely be the other control samples inoculated with bacteria not associated with plastic
degradation. One possibility of results includes a lower survival of copepods in samples
inoculated with fewer bacteria. This would happen if toxic byproducts were not an important
factor. Less survival would be linked to less nutrition compared to samples with more bacteria.
Another possible set of results would show less survival in the samples inoculated with more
bacteria. If this happened, it may be reasonable to assume the byproducts of plastic degradation
have some effect on the survival of copepods.
Implications
These experiments are important steps to understand the significance of the plastic
problem in the oceans. If results show byproducts of plastic degradation by large amounts of
bacteria are not toxic and can support higher trophic life, then the next step of experiments can
proceed. The next step in the process would be to not only include copepods, but also include
other higher organisms. Copepods may be able to survive, but it is important to know if their
predators can survive in these artificial conditions. Eventually, it will be important to take these
experiments to the field. Real world studies reveal insights not capable of prediction in
laboratory settings because of uncontrollable factors. It is the hope that these results provide the
foundation to a feasible solution to the plastic problem our oceans face.
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Candidacy
I believe I am the most valuable candidate for this research position. I am enthusiastic
about this project because I am fascinated with the microbial world. I have prior experience in
marine microbiology. My time at Saddleback College in Mission Viejo has allowed me to
perform two separate water quality experiments dealing with microbes. I have experience
presenting scientific data both visually and orally. My Bachelor of Science in Biology provides
me with a base knowledge of biological communities. It is my goal to expand on this knowledge
through this project.
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Works Cited
1. Eriksen M. et al, (2014). Plastic Pollution in the World's Oceans: More than 5 Trillion
Plastic Pieces Weighing over 250,000 Tons Afloat at Sea. PLOS One, 9(12).
2. Henry, C. et al, (2013). The Plastic-Associated Microorganisms of the North Pacific
Gyre. Marine Pollution Bulletin, 75(2), 126-132.
3. Zettler, E. (2013). Life in the "Plastisphere": Microbial Communities on Plastic Marine
Debris. Environmental Science Technology, 47, 7137-7146.
4. Balasubramanian, V. (2014). High-density polyethylene (HDPE)-degrading potential
bacteria from marine ecosystem of Gulf of Mannar, India. Letters in Applied
Microbiology, 51(2), 205-211.
5. Harshvardan, K. et al, (2013). Biodegradation of low-density polyethylene by marine
bacteria from pelagic waters, Arabian Sea, India. Marine Pollution Bulletin,
77(1), 100-106.
6. Reisser, J. (2014). Millimeter-Sized Marine Plastics: A New Pelagic Habitat for
Microorganisms and Invertebrates. PLOSone, 10(1371).
7. Sanchez, O., & Diestra, E. (2005). Molecular Characterization of an Oil-Degrading
Cyanobacterial Consortium. Microbial Ecology, 50(4), 580-588.